Unit 3 Mastery Quiz #2

Describe the difference between elastic and inelastic collisions. 

Answer explanation

In elastic collisions, objects start separate, collide, and bounce off. In inelastic collisions, objects start separate, collide, and become stuck together. 

Describe the difference between recoil and moving separation.

Answer explanation

In recoil, objects at rest start attached and are forced to separate due to an internal force. The same occurs in moving separation except that objects do not start at rest (they are in motion at some nonzero velocity while attached).

Which of the following has the LEAST amount of momentum?

• A 750 kg car traveling at 25.0 m/s

• A 210 kg sailplane traveling at 90 m/s

• A 4,650 kg motorboat traveling at 5.0 m/s.

• A 30,000 kg truck traveling at 0.75 m/s

Answer explanation

Use the following formula on EACH answer choice:

p = m x v

The one with the LEAST amount of momentum is the car.

Which of the following has the GREATEST amount of momentum?

• A 750 kg car traveling at 25.0 m/s

• A 210 kg sailplane traveling at 90 m/s

• A 4,650 kg motorboat traveling at 5.0 m/s.

• A 30,000 kg truck traveling at 0.75 m/s

Answer explanation

Use the following formula on EACH answer choice:

p = m x v

The one with the LEAST amount of momentum is the car.

Cart X (m = 3.0 kg) is traveling to the right at 4.00 m/s toward Cart Y. Cart Y (m = 9.00 kg) is traveling to the left at 1.33 m/s.

Which cart has the larger magnitude of momentum, and why?

• Cart X has the larger magnitude of momentum because it has a larger magnitude of velocity.

• Cart X has the larger magnitude of momentum because it has the larger product of mass and velocity.

• Cart Y has the larger magnitude of momentum because it has a larger mass.

• Cart Y has the larger magnitude of momentum because it has the larger product of mass and velocity.

Johnny spits out a wad of chewed bubble gum, giving the gum 2X units of momentum. The gum collides and sticks to a small box that is initially at rest.

What type of collision occurred between the gum and the box?

• Elastic because the objects stick together

• Elastic because the objects bounce off each other.

• Inelastic because the objects stick together.

• Inelastic because the objects bounce off each other.

Cart X (m = 3.0 kg) is traveling to the right at 4.00 m/s toward Cart Y. Cart Y (m = 9.00 kg) is traveling to the left at 1.33 m/s.

Cart X and Cart Y collide inelastically.

Calculate the total momentum of the two-cart system after the collision.

HINT: MAKE SURE YOU KNOW THE DIRECTION OF THE CARTS!!

• 0.03 kg*m/s

• 2.67 kg*m/s

• 5.22 kg*m/s

• 23.9 kg*m/s

Which of the following has the MOST amount of momentum?

• A 500 kg motorcycle traveling at 30.0 m/s

• A 300 kg bicycle traveling at 100 m/s

• A 5,000 kg ship traveling at 10.0 m/s.

• A 50,000 kg train traveling at 1.2 m/s

Cart A (m = 2.0 kg) is traveling to the right at 5.00 m/s toward Cart B. Cart B (m = 10.00 kg) is traveling to the left at 2.00 m/s.

Which cart has the larger magnitude of momentum, and why?

• Cart A has the larger magnitude of momentum because it has a larger magnitude of velocity.

• Cart A has the larger magnitude of momentum because it has the larger product of mass and velocity.

• Cart B has the larger magnitude of momentum because it has a larger mass.

• Cart B has the larger magnitude of momentum because it has the larger product of mass and velocity.

Johnny throws a baseball, giving the baseball 3X units of momentum. The baseball collides and bounces off a wall that is initially at rest.

What type of collision occurred between the baseball and the wall?

• Elastic because the objects stick together

• Elastic because the objects bounce off each other.

• Inelastic because the objects stick together.

• Inelastic because the objects bounce off each other.