posted by micky .
A small boy is flipping a piece of cake across the lunch room at school. He uses a fork as a catapult by holding the handle on the table and pressing on the back of it with his thumb. Only part of the energy delivered to the fork goes into the accelerating the cake, however, as the rest goes into the moving the fork. The tines of the fork move through a distance of 15cm as the boy applies a force of 40N with his thumb through a distance of 5 cm. Only 60% of the energy is transmitted to the cake.
A. How much energy does the boy impart to the fork and cake together?
B. How much energy is imparted to the cake?
C. What force act on the cake?