Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity ...
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Transcript of Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity ...
![Page 1: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/1.jpg)
Chapter 12Chapter 12What is Motion?What is Motion?
Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum
![Page 2: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/2.jpg)
MotionMotion
Problem: Is your desk moving?
We need a frame (point) of reference...a nonmoving point from which
motion is measured
![Page 3: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/3.jpg)
MotionMotion
MotionChange in position in relation to
a point of reference.
Reference point
Motion
![Page 4: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/4.jpg)
MotionMotion
Problem:You are a passenger in a car
stopped at a stop sign. Out of the corner of your eye, you notice a tree on the side of the road begin to move forward.
You have mistakenly set yourself as the reference point.
![Page 5: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/5.jpg)
SpeedSpeed
Speed rate at which an object moves distance traveled per unit time
time
distancespeed
sd
t
![Page 6: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/6.jpg)
SpeedSpeed
Instantaneous Speedspeed at a given instant
•ex - the car is going 35 mph right now
Average Speed The average speed of the entire journey
time total
distance totalspeed avg.
![Page 7: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/7.jpg)
VelocityVelocity
Problem:A storm is 10 km away and is
moving at a speed of 60 km/h. Should you be worried?
It depends on the storm’s direction!
![Page 8: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/8.jpg)
VelocityVelocity
Velocityspeed in a given directionVelocity can change even when
the speed is constant!
![Page 9: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/9.jpg)
Calculations of Calculations of Speed & VelocitySpeed & Velocity
Your neighbor skates at a speed of 4 m/s. You can skate 100 m in 20 s. Who skates faster?
GIVEN:
d = 100 m
t = 20 s
s = ?
WORK:
s = d ÷ t
s = (100 m) ÷ (20 s)
s = 5 m/s
You skate faster!vd
t
![Page 10: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/10.jpg)
Calculations of Calculations of Speed & VelocitySpeed & Velocity
Sound travels 330 m/s. If a lightning bolt strikes the ground 1 km away from you, how long will it take for you to hear it?
GIVEN:
v = 330 m/s
d = 1km = 1000m
t = ?
WORK:
t = d ÷ v
t = (1000 m) ÷ (330 m/s)
t = 3.03 s
vd
t
![Page 11: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/11.jpg)
Graphing Speed & VelocityGraphing Speed & Velocitydistance vs. time graphthe slope is = tospeed steeper slope meansfaster speedstraight line meansconstant speedflat line meansno motion
Distance-Time Graph
A
B
![Page 12: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/12.jpg)
Graphing Speed & VelocityGraphing Speed & Velocity
Who started out faster? A (steeper slope)
Who had a constant speed? A
Describe B from 10-20 min. B stopped moving
Find their average speeds. A = (2400m) ÷ (30min)
A = 80 m/min B = (1200m) ÷ (30min)
B = 40 m/min
Distance-Time Graph
A
B
![Page 13: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/13.jpg)
0
100
200
300
400
0 5 10 15 20
Time (s)
Dis
tan
ce (
m)
Distance-Time Graph
Graphing Speed & VelocityGraphing Speed & Velocity
Acceleration is indicated by a curve on a Distance-Time graph.
Changing slope = changing velocity
![Page 14: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/14.jpg)
AccelerationAcceleration
Acceleration the rate of change of velocitychange in speed or direction
t
vva if
a: acceleration
vf: final velocity
vi: initial velocity
t: time
a
vf - vi
t
![Page 15: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/15.jpg)
AccelerationAcceleration
Positive acceleration “speeding up”
Negative acceleration “slowing down”
![Page 16: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/16.jpg)
Acceleration CalculationsAcceleration CalculationsA roller coaster starts down a hill at 10 m/s.
Three seconds later, its speed is 32 m/s. What is the roller coaster’s acceleration?
GIVEN:
vi = 10 m/s
t = 3 s
vf = 32 m/s
a = ?
WORK:
a = (vf - vi) ÷ t
a = (32m/s - 10m/s) ÷ (3s)
a = 22 m/s ÷ 3 s
a = 7.3 m/s2a
vf - vi
t
![Page 17: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/17.jpg)
Acceleration CalculationsAcceleration CalculationsHow long will it take a car traveling 30 m/s
to come to a stop if its acceleration is - 3 m/s2?
GIVEN:
t = ?
vi = 30 m/s
vf = 0 m/s
a = -3 m/s2
WORK:
t = (vf - vi) ÷ a
t = (0m/s-30m/s)÷(-3m/s2)
t = -30 m/s ÷ -3m/s2
t = 10 sa
vf - vi
t
![Page 18: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/18.jpg)
Graphing AccelerationGraphing Acceleration
0
1
2
3
0 2 4 6 8 10
Time (s)
Sp
ee
d (
m/s
)
Speed-Time Graph
slope =
straight line =
flat line =
acceleration +vel = speeds up -vel = slows down
constant accel.
no accel. (constant velocity)
![Page 19: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/19.jpg)
Graphing AccelerationGraphing Acceleration
0
1
2
3
0 2 4 6 8 10
Time (s)
Sp
ee
d (
m/s
)
Speed-Time GraphSpecify the time period
when the object was... slowing down
5 to 10 seconds speeding up
0 to 3 seconds
moving at a constant speed 3 to 5 seconds
not moving 0 & 10 seconds
![Page 20: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/20.jpg)
MomentumMomentum
All moving objects have momentum Momentum depends on the mass of the
object and the velocity with which it is traveling
Formula for calculating momentum
momentum = mass x velocity
m
p
v
![Page 21: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/21.jpg)
Conservation of MomentumConservation of Momentum
The total momentum of any group of objects remains the same unless outside forces act on the objects.
Ex. 2 billiard balls hit into one another.
The total momentum of the 2 balls before they collide is the same as the total momentum of the two balls after they collide.
![Page 22: Chapter 12 What is Motion? Describing Motion Frame of Reference Motion Speed & Velocity Acceleration Momentum.](https://reader035.fdocuments.net/reader035/viewer/2022062304/56649d1f5503460f949f26dd/html5/thumbnails/22.jpg)
Momentum CalculationsMomentum CalculationsWhat is the momentum of a 0.3 kg bluejay
flying at 17 m/sec?
GIVEN:
p = ?
v = 17 m/s
m = 0.3 kg
WORK:
p = m x v
p = (0.3 kg)x(17 m/s)
p = 5.1 kg x m/sec
mp
v