1. A boy pulls a wagon with an 80N force directed 25 degrees above the horizontal a distance of 30m.

a. How much work does the boy do?

b. How much work does he do if the force is directed parallel to the ground?

2. A car hits a pile of dirt and is stopped in .80m. The work done on the car by the sand is -6.0 x10^5J.

a. What is the average force the sand exerts on the car?

b. Explain why the work done by the sand is negative.

c. If the stopping distance is doubled, how does this change the stopping force?

3. A mule tows a barge down a 1.0 kilometer canal. If the mule pulls the barge with a 400N force at an angle of 20 degrees, how much work does it do?