試題詳解

10、 In Figure 10, a horizontal force of 500 N acts on a block of weight 1.5 kN placed on an inclined plane. The coefficients of friction between the block and the plane are 0.25 μs = and 0.20 μk = . What is the actual frictional force? 
(A) 200N
(B) 500 N
(C) 300 N
(D) 450 N。