if a 12kg ball rolls down a ramp at 3 m/s and crashes into a pillow and it takes 0.65 s to stop the ball what is the momentum of the ball and the force exerted by the pillow? I would like to know the formula on how to figure this out.

Momentum before impact = M*V = 12*3

= 36 kg m/s.

Force exerted = Impulse / decel. time)
= (Momentum change)/(deceleration time)
= 36/0.63 = ___ Newtons