Suppose that the nozzle of a fire hose emits a stream of water at a velocity of 30 m/s and
a rate of 10 kg/s. Assuming that the water in the hose is moving at 10 m/s, how much force
must the nozzle exert on the water?
(A) 300 N.
(B) 200 N.
(C) 0.
(D)100 N.
Suppose that the nozzle of a fire hose emits a stream of water at a velocity of 30 m/s and
a rate of 10 kg/s. Assuming that the water in the hose is moving at 10 m/s, how much force
must the nozzle exert on the water?
(A) 300 N. --- No.
The change in velocity is
30 m/s - 10 m/s = 20 m/s.
Suppose that the nozzle of a fire hose emits a stream of water at a velocity of 30 m/s and
a rate of 10 kg/s. Assuming that the water in the hose is moving at 10 m/s, how much force
must the nozzle exert on the water?
(B) 200 N. --- Yes.
Rate of momentum change =
10 kg/s x 20 m/s = 200 kg m/s
= 200 N.
Suppose that the nozzle of a fire hose emits a stream of water at a velocity of 30 m/s and
a rate of 10 kg/s. Assuming that the water in the hose is moving at 10 m/s, how much force
must the nozzle exert on the water?
(C) 0. --- No.
The momentum of the water is changing.
Suppose that the nozzle of a fire hose emits a stream of water at a velocity of 30 m/s and
a rate of 10 kg/s. Assuming that the water in the hose is moving at 10 m/s, how much force
must the nozzle exert on the water?
(D)100 N. --- No.
The change in velocity of the water is 30 m/s - 10 m/s = 20 m/s. Multiply by 10 kg/s.
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