## College Physics (4th Edition)

The water exerts a force of $408~N$ on a person in the crowd.
A person's chest exerts an impulse on the water which is equal in magnitude to the water's change in momentum. Each second, the person's chest exerts a force which stops 24 kg of water moving at a rate of 17 m/s. We can find the average force that the person's chest exerts on the water: $F~t = mv$ $F = \frac{mv}{t}$ $F = \frac{(24~kg)(17~m/s)}{1.0~s}$ $F = 408~N$ Since a person exerts this force on the water, by Newton's third law, the water exerts a force of $408~N$ on a person in the crowd.