Water leaves the fireman's hose at rate of 7.2 kg/s and with a velocity of 21 m/s. Calculate the force exerted by the water jet on the wall of a building.
Splashing agaist the wall will reduce the water's forward momentum to zero. Ignore any backward momentum.
The force will be
momentum flow rate
= (mass flow rate) * V
It will be in Newtons
151.2
To calculate the force exerted by the water jet on the wall of the building, we can use the principle of Newton's second law of motion, which states that force (F) is equal to the rate of change of momentum (p) over time (t).
First, let's calculate the momentum of the water jet. We can do this by multiplying the mass flow rate (m) of the water by its velocity (v).
Given:
Mass flow rate (m) = 7.2 kg/s
Velocity (v) = 21 m/s
Momentum (p) = mass flow rate x velocity
p = m x v
Now, substitute the given values:
p = 7.2 kg/s x 21 m/s
Next, calculate the force (F) exerted by dividing the momentum (p) by the time taken (t).
Given:
Time (t) = 1 second (since we have the mass flow rate per second)
Force (F) = Momentum (p) / Time (t)
F = p / t
Substitute the calculated momentum and time values:
F = (7.2 kg/s x 21 m/s) / 1 s
Now, let's calculate the force:
F = 151.2 N
Therefore, the force exerted by the water jet on the wall of the building is 151.2 Newtons (N).