Question

A fire hoses can expel water at a rate of 9.5kg/s at a rate of 9.5 kg/s with a speed of 24m/s. How much force must the firefighters exert on the hose in order to hold it steady​

Answer 1

Given:-

mass flow rate, $\dot{m}=9.5kg/s$

velocity of jet, v=24 m/s

To Find:-

force exerted by the firefighters on the hose.

Explanation:-

From Impulse momentum equation:-

Force exerted by the firefighters=$\dot{m}\times(v_{i}-v_{f})$

$\text{Put }v_{f}=0\text{ },v_{i}=24m/s\\\\\Rightarrow\text{Force, F}=9.5\times(24-0)=228N$

Answer 2

Answer: 237.5 N

(rounded answer to the correct significant figure is 240 N)

Explanation:

you are given the rate fired and the velocity. This rate can be used instead of mass in the formula F = m(vf - vi).

m = 9.5

vf = 24

vi = 0

F = (9.5)(24 - 0)

F = 237.5