42. A 5.0 kg block of steel slides down a ramp with acceleration 0.40 m / s 2 directed down the ramp. The ramp makes an angle of o 37 with the horizontal. What is the coefficient of kinetic friction between the block and the ramp?
(A) 0.50
(B) 0.70
(C) 0.25
(D) 0.75
(E) 5.0