40. A truck is brought to a stop when its brakes are applied. What type of energy conversion takes place?
Answer: A
Kinetic energy is converted into thermal energy.
When a truck's brakes are applied, the kinetic energy of the moving truck is transformed into thermal energy due to friction in the brake system.
A) Kinetic energy is converted into thermal energy.
This option correctly identifies the energy conversion that occurs when the brakes are applied. The kinetic energy, which is the energy of motion, is dissipated as heat due to the friction between the brake pads and the wheels, resulting in an increase in thermal energy.
B) Elastic potential energy is converted into chemical potential energy.
This option is incorrect because there is no involvement of elastic potential energy in the scenario described. The braking process does not entail a conversion to chemical potential energy, as that would imply a change in chemical bonds rather than a mechanical action.
C) Gravitational potential energy is converted into kinetic energy.
This option is also incorrect. The scenario involves a truck coming to a stop, which means it is losing kinetic energy rather than gaining it. Gravitational potential energy relates to the height of an object and is not relevant to the braking process.
D) Chemical potential energy is converted into gravitational potential energy.
This option is incorrect as well. Chemical potential energy refers to the energy stored in chemical bonds, which is not applicable in this context. The truck's stopping process does not involve a change in gravitational potential energy.
Conclusion
The correct answer, A, accurately reflects the energy transformation that takes place when a truck stops due to braking, where kinetic energy is converted into thermal energy. All other options fail to describe the relevant energy changes involved in the braking process, focusing instead on unrelated forms of energy.