Figure 1.             The Physical forces acting on a Rolling Ball can be seen in Figure 1. Since the ball is

neither rising, nor falling into the ground, the normal force, N, is equal to the Force of gravity, F_g. The frictional force acting on the ball, F_f, is greater than zero only whenthe ball is in motion on the ground.

If a player were to strike the ball, we would need to use the equation for momentum, where the final and initial momentums are equal: p_f=p_i (p_i=m_iv_iand p_f=m_fv_f). The initial mass and velocity of the player, a, would be equal to final mass and velocity of the ball, b. This would essentially be a completely elastic equation: m_av_a=m_bv_b+F_f, and a negative frictional force would be added because it is in the opposite direction of the ball's movement.