Problem 7-35 Work-energy theorem

A girl pulls a box of mass 20.8kg across the floor. She is exerting a force on the box of 95.6N, inclined at 35.0 above the horizontal. The kinetic friction force on the box has a magnitude of 75.5N. Use the work-energy theorem to determine the speed of the box after being dragged 0.750m, assuming it starts from rest. [Ans. 0.45m/s]


What is the correct FBD for this problem?

Three possible FBDs; A, B, C

(A)

(B)

(C)