These days, however, the circles to show which of the following have constant potential energy, and which has changing potential energy-a box sits on a high shelf without moving. A package of pasta falls off a shelf and drops towards the ground. A grocery cart rolls across a flat parking lot. A grocery clerk raises a can to put it on the shelf.
- The box sitting on a high shelf without moving has constant potential energy because it is not changing its position and therefore its potential energy remains the same.
- The package of pasta falling off a shelf and dropping towards the ground has changing potential energy because its position is changing as it falls towards the ground.
- The grocery cart rolling across a flat parking lot has constant potential energy because it is not changing its position vertically and therefore its potential energy remains the same.
- The grocery clerk raising a can to put it on the shelf has changing potential energy because the can's position is changing vertically as it is being lifted.