In: Physics
To contain a violent mob, the riot squad approaches with fire hoses. Suppose that the rate of flow of water through a fire hose is 24 kg/s, and the stream of water from the hose moves at 17 m/s. What force is exerted by such a stream on a person in the crowd? Assume that the water comes to a dead stop against the person's chest.
We have force F = Δp/Δt
= Δ(mv)/Δt
Here the velocity is constant.
Therefore F = v Δm/Δt
Given the speed of water v = 17 m/s
And the rate of flow of water Δm/Δt = 24 kg/s
Then force exerted by the stream of water on the person
F = (17m/s)(24kg/s)
= 408 N
Then force exerted by the stream of water on the person is 408 N.