8.13 Exercise Problems ) Problem 8.1 Figure 8.18 shows a person pushing a block of mass m on a surface that makes an angle 0 with the horizon- tal. The coefficient of kinetic friction between the block and S the inclined surface is . i 1 f 9 Fig. 8.18 Problem 8.1 e If the person is applying a force with constant magnitude P and in a direction parallel to the incline, show that the acceleration of the block in the direction of motion can be expressed as: ax = P m - g(cos + sin 0).