A jet of water flowing from a hose at 18 m/s is directed against a wall.If the mass flow in the fluid stream is 2.0 kg/s,what force is the water applying to the wall if backsplash is negligible?
A)36 N
B)0.11 N
C)38 N
D)350 N
E)34 N

Question

Quizplus · Accepted Answer

The force applied by the water to the wall can be calculated using the formula for the rate of change of momentum, which is $F = \Delta p / \Delta t$, where $F$ is the force, $\Delta p$ is the change in momentum, and $\Delta t$ is the change in time. Since the water stops upon hitting the wall, its final velocity is 0 m/s, and the change in velocity is equal to its initial velocity (18 m/s). The mass flow rate is 2.0 kg/s, which means 2.0 kg of water hits the wall every second. The change in momentum per second ($\Delta p / \Delta t$) is thus $2.0 \, \text{kg/s} \times 18 \, \text{m/s} = 36 \, \text{N}$, indicating the force applied is 36 N.

A Jet of Water Flowing from a Hose at 18