Question 1

Which of the following best describes an elastic collision?

Accepted Answer

The relative speed of the objects before and after the collision is the same, and the total kinetic energy is conserved.

Question 2

A 0.2 kg cart moving at $$0.5\ \mathrm{m/s}$$ collides with an identical stationary cart on a frictionless track. After the collision, the first cart stops and the second cart moves at $$0.5\ \mathrm{m/s}. $$What type of collision is this?

Accepted Answer

Elastic

Question 3

Which equation correctly expresses the kinetic energy $$K of an $$object with mass $$m$$ and speed $$v$$?

Accepted Answer

$$K = \frac{1}{2} m v^2$

Question 4

In a totally inelastic collision, what happens to the relative velocity of the two objects after the collision?

Accepted Answer

It becomes zero.

Question 5

A tennis ball bounces off the ground and returns to its original shape. What type of process is this, and what happens to the internal energy of the ball?

Accepted Answer

Reversible process; internal energy returns to its original value.

Question 6

During an inelastic collision, the total kinetic energy of the system decreases. According to the law of conservation of energy, what happens to the lost kinetic energy?

Accepted Answer

It is converted to internal energy (such as heat or deformation).

Question 7

Which of the following is a characteristic of a closed system in the context of energy analysis?

Accepted Answer

The only energy changes possible are transformations from one type of energy to another within the system.

Question 8

A cyclist accelerates from rest. Which energy transformation best describes this process?

Accepted Answer

Chemical energy is converted to kinetic energy.

Question 9

A piece of dough is thrown at a wall and sticks to it. What happens to the internal energy of the dough-wall system?

Accepted Answer

It increases.

Question 10

Which of the following statements about energy in a closed system is correct?

Accepted Answer

The total energy remains constant, but it can change forms.

Question 11

A spring-loaded gun fires a ball of putty. Which bar diagram best represents the energy conversion in this process?

Accepted Answer

Decrease in elastic energy, increase in kinetic energy.

Question 12

Which of the following is true for an inelastic collision?

Accepted Answer

The sum of the kinetic energies after the collision is less than before, and the internal energy increases.

Question 13

A pot of water is heated on a gas stove. Once the water starts boiling, what happens to the energy released by the burning gas?

Accepted Answer

It is used to change the phase of the water from liquid to steam.

Question 14

Suppose a fan is unplugged but continues to blow air as the blades slow down. What type of energy is being converted to wind energy after the fan is unplugged?

Accepted Answer

Kinetic energy of the fan blades

Question 15

Two identical carts move toward each other with equal speeds and stick together after the collision, coming to rest. What happens to the total kinetic energy of the system?

Accepted Answer

It is converted to other forms of energy, such as internal energy.

Question 16

Which of the following best describes the state of an object in physics?

Accepted Answer

The object's shape, temperature, and any physical variable that defines the object.

Question 17

A ball falls and bounces off the ground, returning to its original height. Which of the following is true about the process?

Accepted Answer

It is a reversible process.

Question 18

Which of the following is NOT a characteristic of an elastic collision?

Accepted Answer

The states of the colliding objects change permanently.

Question 19

A moving cart collides with a stationary cart of unknown mass. After the collision, the carts move apart with different velocities. What information is needed to determine if the collision was elastic?

Accepted Answer

The masses and velocities of both carts before and after the collision.

Question 20

Which of the following scenarios best illustrates the law of conservation of energy?

Accepted Answer

A compressed spring launches a cart, and the spring's elastic energy decreases as the cart's kinetic energy increases.

Chapter 5: Energy – Collisions, Kinetic Energy, Internal Energy, and Closed Systems

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