Problem 17PE

Water from a fire hose is directed horizontally against a wall at a rate of 50.0 kg/s and a speed of 42.0 m/s. Calculate the magnitude of the force exerted on the wall, assuming the water’s horizontal momentum is reduced to zero.

Solution to 17PE

Step 1 of 2

We need to calculate how much force is exerted on wall by water coming out of a fire hose at a rate of . In order to calculate, we need to revisit the Newton’s second law of motion which states that,

“The rate of change of momentum of a body is directly proportional to the force applied”.

is the force

is momentum

is the time

is the mass of the body

is the velocity.

Thus,

In this question the velocity of the water is given as

The rate in which the mass of water is coming out of hose is given as