Newton's Laws and Oxford United at Fleetwood

Oxford United were brilliant in the second half at Fleetwood. Here's the warm up beforehand. A full description of the kicking of a football is a thing to behold. As the foot hits the ball, the ball exerts a force on the ball to decelerate and stop the ball according to Newton's Second Law. Then a reaction force from the foot acts on the ball by Newton's Third Law. This reaction force then acts to accelerate the ball forward according to Newton's Second Law. Or we could pursue an analysis using momentum. Newton wrote his Second Law as "resultant force = rate of change of momentum". As the foot hits the ball, the ball deforms so there is a definite time frame over which the foot is decelerated. If the force exerted by the ball on the foot is constant, then force x time = change in momentum. Force x time is called IMPULSE. The same impulse must act on ball and foot, so the ball will have the same change in momentum, provided no external force acts. Since momentum = mass x velocity, the ball can have the same momentum as the foot but a different velocity due to differing masses.