Reading Question 18.04

Part A

The 100-lb block is transported a short distance by using two cylindrical rollers, each having a weight of 35 lb. A horizontal force P is applied to the block and the block travels 2 ft to the left. Assuming no slipping occurs at all contact points, which of the following is the correct statement regarding the work done on the left roller by the static frictions at contact points A and B, respectively?

Static friction at A does work, and static friction at B does no work