How much force is necessary to keep a 10-cm diameter fire hose stationary if it shoots water at a velocity of 12 m/s?
A)665 N
B)1130 N
C)4522 N
D)3245 N
E)2356 N

Question

Quizplus · Accepted Answer

The force required to keep the hose stationary is equal to the rate of change of momentum of the water. The cross-sectional area of the hose is π*(0.1/2)^2 m². The volume flow rate is area * velocity = π*(0.1/2)^2 * 12 m³/s. The mass flow rate is volume flow rate * density of water (1000 kg/m³). The force is mass flow rate * velocity = π*(0.1/2)^2 * 12 * 1000 * 12 N, which is approximately 1130 N.

How Much Force Is Necessary to Keep a 10-Cm Diameter