Question

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 force exerted on the wall, assuming the water’s horizontal momentum is reduced to zero.

a) 2.1 x 10^3 N
b) 2.5 x 10^3 N
c) 2.8 x 10^3 N
d) 3.2 x 10^3 N

Answer 1

The force exerted on the wall by the horizontal water stream from a fire hose is found by multiplying the mass flow rate by the velocity, yielding a force of 2100 N, which corresponds to option a) 2.1 x 10³ N.

Step-by-step explanation:

When calculating the force exerted on the wall by water from a fire hose, one must consider the change in momentum of the water as it hits the wall. The rate of change of momentum is equal to the force exerted, following Newton's second law of motion. The water stream's initial horizontal momentum per second is the mass flow rate times the velocity (50.0 kg/s × 42.0 m/s). The final momentum is zero since it comes to a halt when it hits the wall.

To find the force exerted, we use the equation: Force = Change in Momentum / Change in Time. Since the momentum drops to zero and the mass flow rate represents change per second, the force can be calculated by simply multiplying the mass rate by the velocity. Therefore, the force is 2100 N.

The correct answer from the given options is a) 2.1 x 10³ N.