Question

Water is pumped through a hose-pipe at a rate of 20 litres/mim and from the nozzle with the velocity 20 m/s. find the force of reaction on the nozzle in newton
and the usefull power of the pump in watt.

Answer 1

Answer on the Question #50244, Physics, Mechanics | Kinematics | Dynamics

Given:

$$v = 20 \frac{m}{s}$$ $$a = 20 \text{litres/min}$$

Solution:

$$a = 20 \text{litres/min} = \frac{20}{60} \frac{\text{kg}}{\text{s}} = \frac{1}{3} \frac{\text{kg}}{\text{s}}$$

force:

$$F = v \cdot a = \frac{20}{3} \frac{\text{kg} \cdot \text{m}}{\text{s}^2} = \frac{20}{3} N \approx 6.67 N$$

usefull power:

$$P = \frac{F \cdot s}{t} = F \cdot v = \frac{20}{3} \frac{\text{kg} \cdot \text{m}}{\text{s}^2} \cdot 20 \frac{\text{m}}{\text{s}} = \frac{400}{3} \frac{\text{kg} \cdot \text{m}^2}{\text{s}^3} = \frac{400}{3} W \approx 133.3 W$$

Answer:

$$F = 6.67 N \quad \text{force}$$ $$P = 133.3 W \quad \text{usefull power}$$

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