5. A 3.0-kg block is on a horizontal surface. The block is at rest when, at t = 0, a force (magnitude P = 12 N) acting parallel to the surface is applied to the block, causing it to accelerate. The coefficient of kinetic friction between the block and the surface is 0.20. At what rate is the force P doing work on the block at t = 2.0 s?
(A) 58 W
(B) 49 W
(C) 39 W
(D) 64 W
(E) 18 W

答案:登入後查看
統計: 尚無統計資料