Velocity
21
Velocity Definition: the speed and direction of motion of an object. v Measured in meters per second (m/s) Example: The car moved at a velocity of 20 m/s toward the east.
description
v. Velocity. Definition: the speed and direction of motion of an object. Measured in meters per second ( m/s ). Example: The car moved at a velocity of 20 m/s toward the east. a. Acceleration. Definition: the rate of change in velocity as a function of time. - PowerPoint PPT Presentation
Transcript of Velocity
VelocityDefinition: the speed and direction of motion of an object.
v
Measured in meters per second (m/s)
Example: The car moved at a velocity of 20 m/s toward the east.
AccelerationDefinition: the rate of change in velocity as a function of time.
aMeasured in meters per second squared (m/s2)
Example: The falling rock accelerated at a constant rate of 9.8m/s2.
1 s |
2 s |
3 s |
4 s |
Velocity
Acceleration
Mass
Definition: how much the object will resist change to velocity.
m
Measured in kilograms (kg)
Example: The table was hard to move because it had a large mass.
Weight Fgrav
Definition: the force of gravity on an object.
Example: Your weight is less on the Moon than on Earth.
ForceFDefinition: a “pushing” or “pulling” on an object.
Example: I applied a force to move the chair.
Measured in Newtons (N)
Fnorm
F grav
Normal ForceFnorm
Definition: a force perpendicular to the object’s contact surface.
F Fnormnorm
F
FFfrict
norm
grav
Friction
Ffrict
Definition: the force that acts opposite to the motion of one object in contact with another object.
Example: the force of friction opposed the motion of the sliding box, slowing it down.
Fnorm
Fgrav
appfrict
FF
Net ForceΣFDefinition: the vector sum of forces.
netF “Sigma F”
Fnet = 15 N up
Fnet = 0
Neither dog won the tug-of-war because they both pulled on the rope with the same force.
Static Friction
Definition: friction that prevents the sliding motion between two objects.
Measured in Newtons (N)
Example: the static friction between the basketball player’s sneakers and the floor kept him from sliding.
fs
fstaticFnorm
Fgrav
Finish Line
Kinetic Friction
Definition: friction that occurs between two objects when when one object slides against another
Measured in Newtons (N)
Example: the kinetic friction from rubbing my hands together warmed them on the cold winter’s night.
fk
fkineticFnorm
Fgrav
ouch!
ouch!
ouch!
Newton’s first law of motion The Law of Inertia
an object in motion stays in motionwith the same velocity
an object at rest stays at rest unless acted
upon by an unbalanced force
Newton’s second law of motion
is directly related to the magnitude of the force,
and inversely related to the mass of the object
Fnet a
m___=
The acceleration of an object produced by a net applied force
The net force equals mass times acceleration Fnet = ma
F= ma
F= ma
for every action (force) there is an equal and opposite
reaction (force).
Forces
come in
pairs!
Newton’s third law of motion
Example: the angry bird exerts a force on the blocks and the blocks exert an equal and opposite force back.
