# Sample Problem

Sample Problem

The giant stone statues of Easter Island were most likely moved by the prehistoric islanders by cradling each Statue in a wooden sled and then pulling the sled over a runway consisting of almost identical logs acting as rollers.

SOLUTION: One Key Idea is that we can calculate the work done with. Here d is the distance 45 m, F is the magnitude of the net force on the statue from the 25 men, and. Let us estimate that each man pulled with a force magnitude equal to twice his weight.

The Key Idea in determining the system on which the work is done is to see which energies change. Because the statue moved, there was certainly a change in its kinetic energy during the motion.

(b) What was the increase !!.E’h in the thermal energy of the system during the 45 m displacement?

SOLUTION: The Key Idea here is that we can relate,h to the work W done by F with the energy statement of for a system that involves friction.

This would have been a staggering amount of energy for the men to have transferred during the movement of a statue. Still. the 25 men could have moved the statue, and the required energy  does not suggest some mysterious source