Center of Mass, Impulse and Momentum, Collisions

1. 1. Which quantity is always conserved in all types of collisions?

• kinetic energy

• mechanical energy

• momentum

• potential energy

2. In a perfectly elastic collision, what is conserved?

• Only kinetic energy is conserved.

• Only momentum is conserved.

• Neither momentum nor kinetic energy is conserved.

• Momentum and kinetic energy are conserved.

3. 3. If you double the mass of a system but retain its velocity, what happens to its momentum?

• decreases to one-fourth

• decreases to one-half

• increases to twice

• increases to four times

16. 4. What is the coefficient of restitution for an inelastic collision?

• 0

• 1

• from 0 to 1

• between 0 and 1

5. Describe a situation where momentum is conserved but kinetic energy is not.

• A rocket launching into space with fuel expulsion.

• A car crash where two cars collide and stick together.

• A ball rolling down a hill without friction.

• A person jumping off a diving board into a pool.

6. How does the center of mass change when two objects collide?

• The center of mass always moves towards the heavier object.

• The center of mass remains constant if no external forces act on the system.

• The center of mass changes direction with every collision.

• The center of mass is irrelevant in elastic collisions.

7. What would happen to the center of mass of a person if his right leg would be amputated?

• It shifts to the left and upward.

• It shifts to the right and upward.

• It shifts to the left and downward.

• It shifts to the right and downward.

8. Give an example of a real-world scenario where impulse is significant.

• A person lifting a heavy box.

• A car accelerating on a highway.

• A balloon floating in the air.

• A baseball player hitting a ball.

9. In a two-body collision, if one object is at rest, how do you calculate the final velocities?

• Apply the Pythagorean theorem to find the final velocities.

• Use conservation of momentum and kinetic energy formulas.

• Use only the initial velocities of the objects.

• Ignore the mass of the objects in calculations.

10. What happens to kinetic energy in an inelastic collision?

• Kinetic energy is completely converted into potential energy.

• Kinetic energy increases significantly after the collision.

• Kinetic energy is conserved and remains the same.

• Kinetic energy is not conserved and decreases.