Consider a rock interacting gravitationally with the earth, and choose the interaction's potential energy to be zero if the rock is at the ground level. A person standing at the bottom of a well throws the rock vertically upward from $20 \mathrm{~m}$ below ground level. The rock makes it all the way up to $1 \mathrm{~m}$ below ground level before falling back into the well. The total energy of the rock-earth system is

Question

Quizplus · Accepted Answer

The total energy of the rock-earth system is negative because gravitational potential energy is chosen to be zero at ground level, and the rock is below this reference point during its entire motion. The kinetic energy cannot offset the negative potential energy enough to make the total energy positive or zero.

Consider a Rock Interacting Gravitationally with the Earth, and Choose 20 m20 \mathrm{~m}20 m

Consider a Rock Interacting Gravitationally with the Earth, and Choose $20 \mathrm{~m}$