申論題

5. The figure shows a 4.00 kg block on a ramp. We pull on the block with force F = 50.0 N, directly up the ramp. The normal force on the block has magnitude = 13.407 N. The block starts from rest. The angle of the ramp is not given. What is the block's speed (m/s) when we have pulled the block up the ramp through displacement d = 3.00 m?

(A) 12.7 (B) 4.4 (C) 1.2 (D) 8.3 (E) 7.9