Q. A force acts on a block weighing 45.0 N. The block is initially at rest on a plane inclined at angle θ = 18.0° to the horizontal. The positive direction of the x axis is up the plane. The coefficients of friction between block and plane are μs = 0.530 and μk = 0.340. In unit-vector notation, what is the frictional force on the block from the plane when is (a) (-5.40 N) i , (b) (-8.30 N) i , and (c) (-15.0 N) i ?