Momentum

Momentum

and impulse!

and collisions!

and explosions!

Units for momentum are kg*m/s

Multiple Choice

What does m stand for?

• muscle

• mass

• momentum

• meters

Multiple Choice

What does v stand for?

• velocity

• volume

• variable

• voltage

Multiple Choice

What does p stand for?

• momentum

• particle

• pressure

• pounds

Poll

Which one would have more momentum?

• Butterfly

• Truck

• Neither

• Both

Any of those answer choices could be correct!

• While the masses are obviously very different, there is no information given about the velocity

• If the truck is not moving, but the butterfly is, the butterfly would have more momentum (vice versa for the truck)

• If the butterfly and the truck were both moving, it would depend on their velocities

The "P" should be lowercase.

Multiple Choice

What does F stand for?

• force

• friction

• fulcrum

• faux pas

Multiple Choice

What does t stand for?

• temperature

• time

• period

• torque

Multiple Choice

What does J stand for?

• impulse

• jerk

• jolt

• junk

Open Ended

Describe how to find the impulse on a graph and which type of graph you use to evaluate impulse.

Multiple Select

This type of collision conserves momentum (you can select more than one).

• Elastic

• Inelastic

• Perfectly inelastic

Multiple Select

This type of collision conserves kinetic energy (you can select more than one).

• elastic

• inelastic

• perfectly inelastic

The inelastic collision is just opposite. Instead of sticking together, it separates.

Solve the problem on this slide and enter your answers on the next few slides. You will need the momentum of both objects before and after the collision.

Fill in the Blanks

The momentum of the grandma before the collision is (you do not need to include units):

Fill in the Blanks

The momentum of the child before the collision is (you do not need to include units):

Fill in the Blanks

The total momentum of the system before the collision is (you do not need to include units):

Fill in the Blanks

The total mass after the collision is (you do not need to include units):

Fill in the Blanks

The velocity of the system after the collision is (you do not need to include units):

Problem worked out:

• Total momentum of the system before = total momentum after

• mass x velocity of grandma = 480 (before)

• mass x velocity of baby = 0 (before)

• total momentum before the collision = 480 kg*m/s

• This was an inelastic collision, the two objects stuck together, so you have to add the masses. The momentum after the collision still has to remain the same

• mass x velocity = momentum (after), so 120 kg x velocity = 480

• Velocity of the system after the collision = 4 m/s

Solve the problem on this slide and enter your answers on the next few slides. You will need the momentum of both objects before and after the collision.

Fill in the Blanks

The momentum of the left train before the collision is (you do not need to include units):

Fill in the Blanks

The momentum of the right train before the collision is (you do not need to include units):

Fill in the Blanks

The total momentum of the system before the collision is (you do not need to include units):

Fill in the Blanks

The total mass after the collision is (you do not need to include units):

Fill in the Blanks

The velocity of the system after the collision is (you do not need to include units):

Problem worked out:

• Total momentum of the system before = total momentum after

• mass x velocity of left train = 20 (before)

• mass x velocity of right train = 0 (before)

• total momentum before the collision = 20 kg*m/s

• This was an inelastic collision, the two objects stuck together, so you have to add the masses. The momentum after the collision still has to remain the same

• mass x velocity = momentum (after), so 5m x velocity = 20

• Velocity of the system after the collision = 4 m/s

I'm not going to ask you to mathematically solve the center of mass for an object

Just know that when we are evaluating momentum and KE, we are looking at these objects moving in a straight line. We are solving them based on their center of mass.... but these conservation laws will also be true when the object begins to turn about its center of mass in the next unit....