## Conceptual Physics (12th Edition)

a. F d = (100 N)(10 m) = 1000 J of work. b. Because of friction, the net work done on the crate is less. $$\Delta KE = Net \;work = net \;force \cdot distance = (100 N – 70 N)(10 m) = 300 J$$ c. The remainder, 700 J, transforms into thermal energy and heats the crate, floor, and surroundings.