A squirrel standing on a branch rolls an acorn toward a hole in the tree. To determine how the potential energy of the acorn changes in relation to the earth, the position of what two objects must be considered?
a
The position of the squirrel on the branch and the earth
b
The position of the acorn and the width of the hole in the tree
c
The position of the acorn and the earth
d
The height of the branch and the position of the acorn