Final answer:
The gravitational potential energy changes for the system that includes the block and Earth, and the system that includes the block, Earth, and hand doing the work. Interaction between the block and Earth is necessary for gravitational potential energy to be considered.Option B & C are the correct answers.
Step-by-step explanation:
The question pertains to which systems change gravitational potential energy as a block moves up an incline. The answer is:
- B. system: block and earth - This system changes gravitational potential energy because as the block moves up, its height relative to Earth increases, which increases its potential energy.
- C. system: block, earth, and hand - This system includes the hand that is doing the work on the block to move it up the incline, adding energy to the system and thereby increasing the block's gravitational potential energy.
The system: block only (A) does not change gravitational potential energy by itself; gravitational potential energy is a property of a system rather than of a single object. It's the relative position within the Earth-object system that matters.
As per Newton's third law, every action has an equal and opposite reaction. Thus, when considering gravitational potential energy, the Earth must be considered as part of the system.
In summary, the gravitational potential energy of a system can be calculated using the equation ΔPEg = mgh, where h is the change in height and g is the acceleration due to gravity.