AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A...
-
Upload
richard-ford -
Category
Documents
-
view
218 -
download
0
Transcript of AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A...
![Page 1: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/1.jpg)
AND chapter 12
MO
TIONFO
RCES
![Page 2: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/2.jpg)
What is a FORCE?
• A FORCE is a push or pull that acts on an object.
• A force can cause a resting object to move• OR…• Accelerate a moving object by:
– changing the object’s speed– direction
![Page 3: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/3.jpg)
![Page 4: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/4.jpg)
How do we MEASURE force?
• Forces can be measured on a spring scale– WEIGHT is a FORCE
• UNITS OF FORCE:– Newton (N)– A Newton is a force that causes a 1 kg mass to
accelerate at a rate of 1 meter per second each second
• Which is written as: 1 N = 1 kg m/s2
![Page 5: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/5.jpg)
Representing Forces
• Forces can be represented with an arrow– The length of the arrow shows strength or
magnitude– Direction of the arrow shows the direction of the
force• Figure 2 on page 357 shows an example of weight
Normal Force
Friction ForceApplied Force
![Page 6: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/6.jpg)
Combining Forces
• Net Force = the overall force acting on an object after all forces are combined
![Page 7: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/7.jpg)
Combining Forces
• Same Direction:
![Page 8: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/8.jpg)
• Opposite Directions:
![Page 9: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/9.jpg)
Net Force
![Page 10: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/10.jpg)
Balanced Forces
• Balanced Forces = the net force is zero, there is no change in the object’s motion
• Question: what are some examples where the net force would equal zero?
![Page 11: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/11.jpg)
ANSWER
• Net force would be zero when:– You play tug-of-war and neither team moves– You arm wrestle and neither person wins– A car using cruise control – constant speed!
![Page 12: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/12.jpg)
![Page 13: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/13.jpg)
Unbalanced Forces
• Unbalanced Forces = the net force acting on an object does not equal zero
![Page 14: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/14.jpg)
• Question: What happens to the object when the net force acting on an object is NOT ZERO, or unbalanced? (like the example below)
![Page 15: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/15.jpg)
Answer• When an unbalanced force acts on an object,
the object accelerates
![Page 16: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/16.jpg)
– 3 examples of a net force causing an object to accelerate
• Pushing against the side of a book & getting it to move• A team winning a game of tug-of-war & pulling the
other team towards them• A person in freefall
![Page 17: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/17.jpg)
![Page 18: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/18.jpg)
Watch video clip: The Effects of Forces on Speed
• On video notes page, draw an example of when the forces are balanced & when they are unbalanced. Then describe the result of these forces.
![Page 19: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/19.jpg)
Try these problems
1. Two tugboats are moving a barge. Tugboat A exerts a force of 3000 newtons on the barge. Tugboat B exerts a force of 5000 newtons in the same direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats in this problem to help you answer the question
![Page 20: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/20.jpg)
• Same direction so add• 3000 N + 5000 N = 8,000 N• + --- = ------
![Page 21: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/21.jpg)
2. Now suppose that Tugboat A exerts a force of 2000 newtons on the barge and Tugboat B exerts a force of 4000 newtons in the opposite direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats in this problem.
![Page 22: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/22.jpg)
• Opposite directions, so subtract• 4000 N – 2000 N = 2000 N• -- =
![Page 23: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/23.jpg)
3. Could there ever be a case when Tugboat A and Tugboat B are both exerting a force on the barge but the barge doesn't move? Draw arrows showing the individual and combined forces in such a situation.
![Page 24: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/24.jpg)
• = 0• Equal in size & opposite in direction
![Page 25: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/25.jpg)
FRICTION
![Page 26: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/26.jpg)
FRICTION• Friction: a force that opposes the motion of
objects that touch as they move past each other
• Without friction, it would be a very different world!!!– Food would not stay on your fork!– Cars would slide all over the road!– Walking would be almost impossible!
• Friction acts at the surface where objects are “in contact”
![Page 27: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/27.jpg)
The 4 Types of Friction
• There are 4 main types of friction:– Static Friction
– Sliding Friction
– Rolling Friction
– Fluid Friction
![Page 28: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/28.jpg)
STATIC FRICTION
• friction force that acts on objects that are not moving
• Static friction always acts in the direction opposite to the applied force
• Examples: – every time you take a step and push off– glass of water sitting stationary on the table
![Page 29: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/29.jpg)
SLIDING FRICTION• a force that opposes the direction of motion
of an object as it slides over a surface• Sliding friction is a weaker force than static
friction– This is why less force is needed to keep an object
moving than it is to start it moving
![Page 30: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/30.jpg)
ROLLING FRICTION• The friction force that acts on rolling objects• Rolling friction is about 100-1000 times less
than static or sliding friction– This is why we use wheeled dollies to move heavy
objects!– In machines, ball bearings, are often used to
reduce friction between two surfaces
![Page 31: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/31.jpg)
FLUID FRICTION• Force that opposes the motion of an object
through a fluid– Water and a mixture of gases such as air are
known as fluids– Example: a submarine moving through water
• The motion of the submarine is slowed by fluid friction• Fluid friction increases as the speed of the object
moving through the fluid increase– So the faster the sub goes, the greater the friction!!!
![Page 32: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/32.jpg)
AIR RESISTANCE• Air resistance is a type of fluid friction
– Remember…gases are considered “fluids”
• Fluid Friction acting on an object moving through the air is called AIR RESISTANCE
![Page 33: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/33.jpg)
GRAVITY
![Page 34: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/34.jpg)
GRAVITY• Gravity: a force that acts between any two
masses– Gravity is an attractive force so it pulls objects
together– Gravity does not require objects to be in contact
for it to act on them• Gravity can act over large distances!!!
![Page 35: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/35.jpg)
More GRAVITY!• Earth's gravity acts downward toward the center
of the Earth.
• There is usually an upward force that acts against gravity to balance out the forces and allow objects to remain still.
![Page 36: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/36.jpg)
FALLING OBJECTS
• QUESTION: What forces are acting on an object as it falls?
![Page 37: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/37.jpg)
• ANSWER: Only two forces acting on a falling object are gravity and air resistance
![Page 38: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/38.jpg)
Forces Acting on Falling Objects
• Gravity causes object to accelerate downward• Air resistance acts in the opposite direction of
the motion– Which means it reduces acceleration
![Page 39: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/39.jpg)
• Recall…what happens to the amount of fluid friction as an object speeds up?
![Page 40: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/40.jpg)
Watch video clip: The Physics of Skydiving
• On the video notes page, describe what is meant by terminal velocity & describe the forces on the skydiver at this point.
![Page 41: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/41.jpg)
Falling Objects• If an object in freefall falls for long enough, the
upward force of air resistance will become equal to the downward force of gravity.
– At this point, the two forces are BALANCED
– Acceleration is zero when forces are balanced
– The object will continue to fall at a constant velocity
![Page 42: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/42.jpg)
Terminal Velocity• Terminal Velocity: the constant velocity of a
falling object when the force of air resistance equals the force of gravity
![Page 43: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/43.jpg)
Projectile Motion
• Projectile Motion: The motion of a falling object (projectile) after it is given an initial forward velocity
![Page 44: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/44.jpg)
Projectile Motion
• Question: What are the ONLY 2 FORCES that act on a projectile???
All 3 balls are experiencing projectile motion!
![Page 45: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/45.jpg)
Projectile Motion
• Answer: Air resistance and gravity!!!
– Refer to figure 9 on page 362 in textbook
– The combination of an initial forward velocity and the downward vertical force of gravity causes the ball to follow a curved path
![Page 46: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/46.jpg)
• If I shoot a bullet horizontally and at the same time drop a bullet from the same height as the gun…which will hit the ground first?
![Page 47: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/47.jpg)
FALLING OBJECTS
• The two bullets WILL hit the ground at the same time!
![Page 48: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/48.jpg)
The two balls fall with the same acceleration and strike the ground at the same time!!!
Remember the “Investigating Freefall Lab” with the marbles? How did that lab compare with the previous statement???
![Page 49: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/49.jpg)
12.2 Newton’s First & Second Laws of Motion
![Page 50: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/50.jpg)
It’s not ALL about Newton…• Aristotle incorrectly proposed that force is required
to keep an object moving at a constant speed• Galileo studied how gravity produces constant
acceleration. He concluded that objects not subjected friction or any other force would continue to move indefinitely
• Newton built off the work of Galileo and later published his work in a book entitled Principia
• Newton summarized his study of force and motion in several laws of motion
![Page 51: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/51.jpg)
1st Law of Motion – Law of Inertia
![Page 52: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/52.jpg)
1st Law of Motion – Law of Inertia
• 1st Law: The state of motion of an object does not change as long as the net force acting on the object is zero
– In other words: Unless an unbalanced force acts, an object at rest remains at rest, and an object in motion remains in motion with the same speed and direction
![Page 53: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/53.jpg)
1st Law – Law of Inertia• Example: A soccer ball resting on the grass
remains motionless until a force is applied to it.
![Page 54: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/54.jpg)
And…
• Example: A soccer ball in motion remains in motion unless a force acts on it.
![Page 55: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/55.jpg)
Why is it called the “Law of Inertia”
• INERTIA: the tendency of an object to resist a change in its motion so…
an object at rest tends to remain at rest (resist moving), and an object in motion tends to remain in motion (resist stopping)
![Page 56: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/56.jpg)
– Remember…soccer ball sat motionless (forces were balanced) until an unbalanced force acted on it
– The ball has inertia– Everything with mass has inertia– The more mass, the more inertia
![Page 57: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/57.jpg)
![Page 58: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/58.jpg)
Inertia…Front-end collision
• Example: Front-end collision • Collision makes car stop suddenly• Since you have inertia you continue moving
forward• Page 364/365 Figure 12
![Page 59: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/59.jpg)
Newton’s Second Law of Motion
![Page 60: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/60.jpg)
2nd Law of MotionRelates the acceleration of an object to the force acting
on it & the object’s mass.
• 2nd Law: The acceleration of an object is equal to the net force acting on it divided by the object’s mass. A = F/M
• In other words, the amount of acceleration an object has depends on:– How hard it is pushed (force)– How heavy it is (mass)
![Page 61: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/61.jpg)
Net ForceAcceleration = --------------
Mass
![Page 62: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/62.jpg)
Acceleration…Force & Mass Relationship
What is the acceleration?
![Page 63: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/63.jpg)
ANSWER
• Acceleration is calculated by dividing the FORCE by the MASS
Acceleration = 100 N / 50 kg A = 2 m/s2
![Page 64: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/64.jpg)
2nd Law– Example: You apply force to a ball when you
throw it • The harder you throw, the more the ball accelerates• If you double the force, the acceleration of the ball
doubles as well• If you double the mass of the ball the acceleration is
cut in half• More Examples:
![Page 65: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/65.jpg)
Important Notes…Regarding Newton’s 2nd Law of Motion
• The acceleration of an object is always in the same direction as the net force.
• In using Newton’s second law, it is helpful to realize that the units N/kg and m/s2 are equivalent
• Newton’s second law also applies when a net force acts in the direction opposite to the object’s motion – producing deceleration (See figure 13, page 368)– This is the principle used by automobile seat belts
• See Math Skills page 367 (in textbook) for extra help
![Page 66: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/66.jpg)
Weight & Mass…What really is the difference?
![Page 67: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/67.jpg)
• We often talk about weight and mass as if they were the same thing
• Weight: is the force of gravity acting on an object.– An object’s weight is the product of the object’s
mass and acceleration due to gravity acting on it.– Written mathematically as w = m x g
![Page 68: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/68.jpg)
Weight lessens as…
Weight will DECREASE if gravity DECREASES!!!
![Page 69: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/69.jpg)
Mass Versus Weight
• Mass is a measure of the inertia of an object,– Measure with a balance
• Weight is a measure of the force of gravity acting on an object – Measure with a spring scale
• Weight = Mass x Acceleration due to gravity– W = mg– Value of g = 9.8 m/s2 (Earth)
![Page 70: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/70.jpg)
Important Note Regarding Units
• Be sure when you use the weight formula or Newton’s second-law formula that you use the CORRECT units!!!
• Force (F or W) in N (newtons)• Acceleration (a or g) in m/s2 (meters per
second per second)• Mass (m) in kg (kilograms)
![Page 71: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/71.jpg)
Practice Problem
• If an astronaut has a mass of 112 kilograms, what is his weight on Earth where the acceleration due to gravity is 9.8 m/s2?
• What would his weight be on the moon (g=1.62 m/s2)?
![Page 72: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/72.jpg)
Answer to Practice Problem
• ON EARTH: Weight = Mass Acceleration due to gravity W = 112 kg x 9.8 m/s2
W = 1097 kgm/s2 = 1097 N
• ON MOON:– W = 112 kg x 1.62 m/s2
– W = 181 kgm/s2 = 181 N
![Page 73: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/73.jpg)
Mass & Weight are Related• Doubling the mass of an object also doubles the
object’s weight (if gravity remains the same)• If Gravity changes then…
– Example: Think about the astronaut above… – On the moon, the acceleration due to gravity is only
about 1/6 that on Earth– Thus, the astronaut weighs only about 1/6 as much
on the moon as on Earth
• In both locations, the mass of the astronaut is the same!
![Page 74: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/74.jpg)
12.3 Newton’s 3rd Law of Motion
![Page 75: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/75.jpg)
Forces CAN’T Exist Alone…• Forces always exist in pairs.
• According to Newton’s 3rd law of motion, whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
• These two forces are called action and reaction forces
![Page 76: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/76.jpg)
Action – Reaction Forces• Example: The book lying on the table is
exerting a downward force on the table, while the table is exerting an upward reaction force on the book.
![Page 77: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/77.jpg)
Newton’s Third Law Ex: A rocket
![Page 78: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/78.jpg)
• More Examples: Jumping off of a raft
Action force = you push on the raftReaction force = raft pushes back
A swimmer in a poolAction force = swimmer’s arm pushes on waterReaction force = water pushes back on swimmer
![Page 79: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/79.jpg)
Action – Reaction Forces• Question: Since these action/reaction forces
are equal in size and opposite in direction then why don’t they cancel each other out and produce a net force of zero?
![Page 80: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/80.jpg)
Action – Reaction Forces
• Because the action/reaction forces do not act on the same object!
• Swimmer Example: – The action force acts on the water– The reaction force acts on the swimmer
![Page 81: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/81.jpg)
Momentum
• Momentum = the product of an object’s mass and it’s velocity
• An object with a large momentum is hard to stop
![Page 82: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/82.jpg)
• Momentum = mass X velocity
• Practice Problem: What is the momentum of a rock with a mass of 0.5kg that is moving at a velocity of 5m/s?
![Page 83: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/83.jpg)
• Momentum = 0.5kg X 5m/s = 2.5kg x m/s– The units do NOT cancel!
![Page 84: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/84.jpg)
• Momentum can be transferred from one object to another during a collision
![Page 85: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/85.jpg)
12.4 – Universal Forces
![Page 86: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/86.jpg)
Four Universal Forces
1. Electromagnetic forces- only forces that both attract and repel.
2. Strong Nuclear forces- holds neutrons & protons together
3. Weak Nuclear forces- attractive force between particles in nucleus
4. Gravitational forces- attractive force between any two objects
![Page 87: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/87.jpg)
GRAVITY• Gravity is the weakest universal force • On a daily basis, you don’t notice the force of
gravity that you exert on objects—this is because your mass is sooooooo small.
• It takes a huge mass like the Earth’s to exert a large gravitational force.
![Page 88: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/88.jpg)
![Page 89: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/89.jpg)
GRAVITY• Gravitational force depends on two things: the
mass of an object and the distance between two objects. – A greater mass will exert a greater gravitational
force on an object.– The greater the distance between two masses
significantly decreases the gravitational force.
![Page 90: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/90.jpg)
Attractive Force of Gravity
![Page 91: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/91.jpg)
![Page 92: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/92.jpg)
GRAVITY…how can it be so weak?• Even though gravity is the weakest universal force, it
is the most effective over large distances.– Gravity holds you on the ground– It holds the moon in orbit around the Earth– It holds the planets in orbit around the Sun– It holds the stars in orbit around their galaxies
![Page 93: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/93.jpg)
Centripetal Force
• The force of gravity from the Earth continuously pulls the moon in a nearly circular orbit around the Earth.
• Centripetal force: center-directed force that continuously changes the direction of an object to make it move in a circle.– As an object moves in a continuous (constant)
circular motion, it is accelerating.– How is it accelerating if it does not change speed?
• Change in direction!!!
![Page 94: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/94.jpg)
Centripetal Force
• It’s a lot like a string tied to an eraser…• The force from the center of the string allows
the eraser to twirl in a circle over your head• As you twirl the eraser, the string exerts a
centripetal force on the eraser.
![Page 95: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/95.jpg)
Centripetal force & Orbital Motion
• Objects need only a centripetal force and their own inertia to maintain an orbit.
• Orbital motion is a balance between the centripetal force and inertia.
• If Centripetal force is stronger it will crash, if inertia is stronger it will fly off into space
![Page 96: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/96.jpg)
• Examples of objects in orbit: – Satellites– Our moon is a natural satellite of our planet
![Page 97: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/97.jpg)
Orbital Motion
http://upload.wikimedia.org/wikipedia/commons/4/4e/Orbital_motion.gif
![Page 98: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/98.jpg)
How is this possible?!?!
Same Place…Same Day…??? HOW!!!???
![Page 99: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/99.jpg)
How is that possible?• Ever been to the seashore? What do you
notice about the level of the water throughout the day? Why does it change? – The gravitational pull from the Moon produces
two tides in the Earth’s oceans as it moves around the Earth.
• One bulge where the moon is closest to the Earth• One bulge where the moon is farthest from the Earth
![Page 100: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/100.jpg)
Tides
• Since the Earth rotates once per day, it results in two high tides and two low tides per day on Earth!
http://home.hiwaay.net/~krcool/Astro/moon/moontides/
![Page 101: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/101.jpg)
Rotation versus Revolution• The Earth moves in two major ways:
– Rotation- the spinning of the Earth on its axis• This rotation causes day and night
– Revolution- the movement of one body in space around another
• When does the Earth show revolution? Revolves around the Sun
– How long does it take for the Earth to revolve?• 365 Days
![Page 102: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/102.jpg)
Ch 13 Forces in Fluids
![Page 103: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/103.jpg)
13.1 Fluid Pressure
• Why is an Aeron chair so much more comfortable than a bicycle seat?
![Page 104: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/104.jpg)
• Pressure = the result of a force distributed over an area
![Page 105: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/105.jpg)
• Ex: the tip of a pencil easily pokes through a sheet of paper while the eraser end does not
• Ex: finger poke vs needle poke
![Page 106: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/106.jpg)
• Pressure = Force/Area• Units of Pressure = N/m2 = Pascal (Pa)
![Page 107: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/107.jpg)
• Practice problem: A box weighing 2700 N is resting on the ground. If the box is covering 1.5 square meters of area, what is the pressure?
![Page 108: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/108.jpg)
• Pressure = 2700 N/1.5 m2 = 1800 Pa = 1.8 kPa
![Page 109: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/109.jpg)
Pressure in Fluids
• Recall: a fluid is a substance that takes the shape of its container, both liquids and gases are fluids
![Page 110: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/110.jpg)
• What happens to the pressure exerted on your body as you dive deeper in a pool?
![Page 111: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/111.jpg)
• Water pressure increases as depth increases
• The relationship between pressure and the depth of a fluid can be shown with this formula: P = d x h x g
• d = density• h = depth• g = accel due to gravity
![Page 112: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/112.jpg)
• Fluid pressure is determined by the type of fluid and its depth
• Which would exert more fluid pressure at a depth of 20 m, Lake MI or the Gulf of Mexico?
![Page 113: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/113.jpg)
Air Pressure & the Atmosphere
• We live at the bottom of a vast ocean of air. • The weight of the Earth’s atmosphere exerts
pressure. At sea level = 101 kPa
• We refer to a certain altitude instead of a depth
• Air pressure decreases as the altitude increases
![Page 114: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/114.jpg)
• Why do your ears pop while traveling up a mountain?
![Page 115: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/115.jpg)
• The difference in pressure between the inside of your ear and the air outside causes air to pass through a small tube within your ear to equalize the pressure.
• This is the popping sensation you feel
![Page 116: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/116.jpg)
• The atmosphere is exerting more than 1000 N on the top of your head. Why aren’t we crushed by this?
![Page 117: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/117.jpg)
• The inside of your body exerts pressure against the air pressure outside which balances and results in a net force of zero.
![Page 118: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/118.jpg)
Bernoulli’s Principle
• Bernoulli’s Principle = as the speed of a fluid increases, the pressure within the fluid decreases
• Demo: take a piece of paper and blow across the top of the paper
![Page 119: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/119.jpg)
Wings & Lift
• The ability of birds and airplanes to fly is explained by Bernoulli’s principle
![Page 120: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/120.jpg)
• The air traveling over the top of the curved wing travels faster so the pressure is less which create the lift
![Page 121: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/121.jpg)
![Page 122: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/122.jpg)
![Page 123: AND chapter 12 MOTION FORCES. What is a FORCE? A FORCE is a push or pull that acts on an object. A force can cause a resting object to move OR… Accelerate.](https://reader036.fdocuments.net/reader036/viewer/2022062721/56649f1f5503460f94c3712e/html5/thumbnails/123.jpg)