A 1.5 kg rock is dropped from a height of 2.0 meters onto a spring that compresses and brings the rock to rest. (Assume no losses to thermal
energy.) How much energy is in the system before the drop.

29.4 J

Explanation:

Before the drop, the system has only the gravitational potential energy, and this energy us given by mass×gravity×height:

1.5•9.8•2 = 29.4 J

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)