Complete the statement. Assume that Duncan's mass did not change.
The gravitational potential energy stored between Duncan and Earth () as he rode the escalator.

 - increased
 - stayed the same
 - decreased
Think about how the distance between Duncan and the center of Earth changed.
The second floor is higher than the first floor. As he rode the escalator toward the second floor, the distance between Duncan and the center of Earth increased. So, the gravitational potential energy stored between Duncan and Earth increased as he rode the escalator.