Problem: Suppose that the rate of flow of water through a fire hose is 21.4 kg/s and the stream of water from the hose moves at 14.9 m/s. What force is exerted by such a stream

Given Information:

mass flow rate = 21.4 kg/s

change in velocity = 14.9 m/s

Required Information:

Force = ?

Force = 318.86 N

Explanation:

We know that force is equal to change in momentum over time

F = Δp/t

Where change in momentum is

Δp = m(v₂² - v₁²)

so force becomes

F = m(v₂² - v₁²)/t

Where m/t is basically mass flow rate 21.4 kg/s

F = 21.4 kg/s*(v₂² - v₁²)

The change in velocity is given as

v₂² - v₁² = 14.9 m/s

F = 21.4 kg/s * 14.9 m/s

F = 318.86 kg.m/s²

1 kg.m/s² is equivalent to 1 Newton of force

F = 318.86 N

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.