Lesson 6.5

Lesson 6.5

by Mark AHS

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​Videos To Watch

​Newton's Cradle

​Blob Jump

​COM Example

​A 2kg toy car moving 8 m/s hits and sticks to a 3kg car that is at rest.

1. What is the momentum of Car 1 before the collision?

2. What is the total momentum of the system before the collision?

3. What is the total momentum of the system after the collision?

4. What is the velocity of the two cars after the collision?

​COM Example #2

​A 100kg football player running 8 m/s hits and grabs onto a 125kg Player that is at rest.

1. What is the momentum of Player 1 before the collision?

2. What is the total momentum of the system before the collision?

3. What is the total momentum of the system after the collision?

4. What is the velocity of the two players after the collision?

​Impulse and Momentum

​Impulse is the amount of time a force is applied. 

• Impulse = F x t

• Impulse is always equal to the change in momentum of an object as well. 

• F x t = m x v

  • Please ensure that you completely understand the star above 100%

****Class Discussion on Impulse/momentum in regards to safety****

​What does impulse mean to us?

​No matter how an accident occurs, if you’re involved in an impact, the change in momentum is the same for you at a given speed. You can’t control your mass or your velocity. So, m x v is the same for you. 

• That means F x t is the same for you as well. 

• The only thing you really have control over is the time the impact takes place. 

• Since, for a given collision, F x t has to equal the same number, A big t means a smaller F. 

• If you can increase impact time, the impact force on you will be smaller. That’s why we have airbags, crumple zones, landing pads for stuntmen, etc.

​Videos to watch

​Stuntman record jump

​Old car vs new car crash test

Multiple Choice

An 8kg bowling ball moves with a velocity of 7 m/s. What is the momentum of the bowling ball?

• 26 kgm/s

• 36 kgm/s

• 46 kgm/s

• 56 kgm/s

Multiple Choice

The momentum of an object depends upon the object's ___________&_____________.

• size and shape

• mass and speed

• mass and veloctiy

• mass and energy

Multiple Choice

In any collision (crash) the ______ is ALWAYS constant

• Total Momentum
• total speed
• total Velocity
• Energy

Multiple Choice

A 0.250 kg cart moving at 0.400 m/s has how much momentum?

• 0.1 kg-m/s
• 1 kg-m/s
• 10 kg-m/s
• 100 kg-m/s

Multiple Choice

Which object listed below has the greatest momentum?

• A 0.05 kg object rolling at 0.2 m/s.
• A 0.15 kg object rolling at 2 m/s.
• A 0.15 kg object rolling at 1 m/s
• A 0.4 kg object rolling at 2 m/s.

Multiple Choice

The total momentum before a collision is _________ the total momentum after a collision.

• equal to 
• less than 
• more than
• It depends on the type of collision

Multiple Choice

If two objects have the same mass, then the faster moving object has ____________ momentum.

• more 
• less
• the same

Multiple Choice

A 4kg objects slides across ice without friction at a velocity of 6 m/s. The object hits and sticks to a 2kg object that is initially at rest. What is the momentum of the 4kg object?

• 24 kgm/s

• 16 kgm/s

• 8 kgm/s

• 0 kgm/s

Multiple Choice

A 4kg objects slides across ice without friction at a velocity of 6 m/s. The object hits and sticks to a 2kg object that is initially at rest. What is the momentum of the 2kg object?

• 24 kgm/s

• 16 kgm/s

• 8 kgm/s

• 0 kgm/s

Multiple Choice

A 4kg objects slides across ice without friction at a velocity of 6 m/s. The object hits and sticks to a 2kg object that is initially at rest. What is the total momentum of the 2 object system before the collision?

• 24 kgm/s

• 16 kgm/s

• 8 kgm/s

• 0 kgm/s

Multiple Choice

A 4kg objects slides across ice without friction at a velocity of 6 m/s. The object hits and sticks to a 2kg object that is initially at rest. What is the total momentum of the 2 object system after the collision?

• 24 kgm/s

• 16 kgm/s

• 8 kgm/s

• 0 kgm/s

Multiple Choice

A 4kg objects slides across ice without friction at a velocity of 6 m/s. The object hits and sticks to a 2kg object that is initially at rest. What is the total velocity of the 2 object system after the collision?

• 16 m/s

• 8 m/s

• 4 m/s

• 0 kgm/s