Physics Momentum study guide

If solving for the vf of an object after a collision but both objects are equal in mass then use the equation…

vf2= (vi1+vf2)-vf

If solving for the vf of an object after a collision but both objects are NOT equal in mass then use the equation…

(m1 x vi1) + (m2 x vi2) = (m1 x vf1) + (m2 x vf2)

what is Newtons 3rd law:

For every action there is an equal, opposite, and simultaneous reaction

If force is applied to an object by the same amount at the same time with the same magnitude then the impulse is…

the same for both objects just in opposite directions

The Term “Action/Reaction Pair” is used to describe what?

wo objects that apply a force on each other

An example of a “Action/Reaction Pair” is

Earth’s gravity pulls you down.  At the same time you pull the Earth up.

A graph example of an “Action/Reaction Pair” is

this graph

The Impulse of an action/reaction pair is…

equal but opposite due to the force being equal but opposite in direction.

When two objects collide they impart a force on each other with impulses that are equal and opposite or unequal and opposite?

equal but opposite impulses.

opposite impulses mean that the objects have an…

instantaneous change in momentum opposite to their initial direction of motion.

The velocity they move with is potentially different due to their ___ being potentially different.

masses

The phenomenon called recoil is

the momentum of the projectile forward is balanced by the momentum of the weapon backward

In recoil the time…

cancels because both objects experience the force for the same time.

As a result, the post collision velocity in recoil is a based on a…

proportion of the masses involved.

If the masses are equal, both objects will recoil with the…

same velocity

If masses are NOT equal in recoil then the velocity with a larger mass will…

recoil with a smaller velocity.

the recoil equation is

v₁ = - (m₂v₂) / m₁

Impulse def:

Force for a given amount of time that changes the acceleration (change in momentum)

Momentum:

The quantity of motion an object has. It's known as “ mass in motion". Meaning all objects that have mass and motion have momentum.

Collision:

When objects try to occupy the same space at the same time.

In an Inelastic Collision:

Kinetic energy is lost

In an Elastic Collision:

Kinetic energy is conserved 

In an Explosion:

 Kinetic energy is gained

In a Perfectly Inelastic Collision:

Kinetic energy is lost and objects have the same velocity

When is the only time an object does not have momentum?

When its not moving

What happens to the momentum of an object if the velocity the object is moving with increases?

Momentum will increase

If a larger force is applied then the time period is…

shorter

If a smaller force is applied then the time period is…

Longer

In an explosion what physically happens to the objects after the collision?

It breaks apart into multiple different objects

A 10 kg object is moving with a velocity of 20 m/s.  What is the magnitude of the object’s momentum?

200 Ns

In this image what is the magnitude of impulse that the tennis racket imparts onto the tennis ball as shown by the graph?

0.9 N*s

How do you find impulse from a graph?

By finding the area under the curve

A 2 kg object is originally moving with a velocity of 10 m/s and comes to rest.  What is the object’s change in momentum and what equation was used?

p = mv was used and the answer is -20Ns