Difficulty: Easy

Average Score: 80%

As a roller coaster car descends a hill, which of the following is true of the kinetic and gravitational potential energies of the car?

Rationale

Kinetic Energy: Increases | Potential Energy: Decreases

As the roller coaster car descends a hill, gravitational potential energy is converted into kinetic energy. This conversion results in an increase in the car's speed, which corresponds to an increase in kinetic energy, while the height of the car decreases, leading to a decrease in gravitational potential energy.

A (Kinetic Energy: Increases | Potential Energy: Decreases) CORRECT

This choice accurately describes the relationship between kinetic and gravitational potential energy during the descent of the roller coaster. As the car moves downwards, it loses height, which reduces its potential energy, while simultaneously its speed increases, resulting in a rise in kinetic energy, exemplifying the conservation of mechanical energy.

B (Kinetic Energy: Decreases | Potential Energy: Increases) YOUR ANSWER

This choice is incorrect because it suggests that as the car descends, its speed decreases, which contradicts the principles of energy conversion. As the car descends, it gains speed, which means kinetic energy must increase, not decrease.

C (Kinetic Energy: Remains constant | Potential Energy: Decreases) YOUR ANSWER

This option is also incorrect because it claims that kinetic energy remains constant during the descent. In reality, as the car descends, potential energy decreases while kinetic energy must increase due to the conversion of energy from one form to another.

D (Kinetic Energy: Remains constant | Potential Energy: Remains constant) YOUR ANSWER

This choice is incorrect as it implies that neither energy type changes during the descent. However, the descent of the roller coaster car inherently involves a conversion of gravitational potential energy to kinetic energy, indicating that both energy types are actively changing.

Conclusion

As a roller coaster car descends a hill, gravitational potential energy is transformed into kinetic energy, leading to an increase in the car's speed. This process illustrates the principle of conservation of energy, where the total mechanical energy remains constant, but the forms of energy—kinetic and potential—shift in response to changes in height. Thus, option A correctly captures this dynamic interplay of energy types.

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