Question

If a block is sitting in a shelf 5 foot high and the same size block is sitting on the shelf above it at 6 feet high. Which has more potential energy? Explain your reasoning.

Answer 1

Step-by-step explanation:

Assuming that not only is the size of the two blocks the same but the MASS is also the same, then the higher block will have more potential energy.

Potential energy is equal to the amount of work required against gravity to position a mass

Work is a force times a distance. PE = W = Fd

As each block has the same mass, they each create the same force which would be their weight mg

PE = W = Fd = mgd

so potential energy is directly proportional to the height of each block

the lower block has potential energy PE = Fd = mg(5)

while the upper block has potential energy PE = mg(6)

above a reference frame origin, possibly the floor.

It is possible that the higher block has less potential energy then the lower block if only the size is considered. If the higher block is a one foot cube of ice at 57.2 lbs and the lower block is a one foot cube of copper at 559 lbs then the lower mass would have much more potential energy because of its much greater mass.

559(5) = 2795 ft•lb of potential energy

57.2(6) = 343.2 ft•lb of potential energy