Question

exam lesson name: energy conversions
exam number: 700697rr
▶ exam guidelines
▶ exam instructions

question 8 of 20 :
select the best answer for the question.

1. the law of conservation of energy states that

○ a. all objects have potential mechanical energy.
○ b. all objects have thermal energy.
○ c. objects that have mechanical energy must maintain mechanical energy.
○ d. energy can’t be created nor destroyed, just transformed.

□ mark for review (will be highlighted on the review page)

<< previous question next question >>

Explanation:

To solve this, we analyze each option based on the law of conservation of energy:

• Option A: Not all objects have potential mechanical energy (e.g., an object at rest on the ground with no height has no gravitational potential energy in a simple sense, and not all objects have other forms of potential mechanical energy). So A is incorrect.
• Option B: The law of conservation of energy is not about all objects having thermal energy. Thermal energy is related to temperature and molecular motion, and this is not the statement of the conservation law. So B is incorrect.
• Option C: Mechanical energy can be converted to other forms of energy (like thermal energy due to friction), so objects with mechanical energy don't have to maintain it. So C is incorrect.
• Option D: The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another (or transferred). This matches the definition.

Answer:

D. energy can't be created nor destroyed, just transformed.