Find the power (in W) of a pump if it can lift 1 tonne of water by 90 m in 30 minutes. (Assume 100% efficiency and use g= 10 m/s 2)
500
Concept:
Gravitational potential energy:
- It is the energy gained or acquired by an object due to a change in its position while present in a gravitational field.
- In simple words, it can be said that gravitational potential energy is the energy related to the force of gravity or gravitation.
- Formula, U = mgh, where, m = mass, g = acceleration due to gravity, h = height
- The SI unit of gravitational potential energy is the joule.
Power:
- It is defined as work per unit time.
- Formula, Power, \(P=\frac{W}{t}\) where, W = work done, t = time
The SI unit of power is the watt.
Calculation:
Given,
Mass m = 1 tonne = 1000 kg, height, h = 90 m, time t = 30 min = 1800 s
Power, \(P=\frac{mgh}{t}\)
\(P=\frac{1000\times 10\times 90}{1800}=500 ~W\)
Hence, the power is 500 W.
Important Questions from Power
Express the power dissipated in a 100 Ω resistor in dB relative to 1 mW, when the voltage across the resistor is 1.0 Vrms
An elevator weighing 500 kg is to be lifted up at a constant velocity of 0.25 m/s. What would be the minimum horsepower of the motor to be used? G = 9.8 m/s2 and there is no frictional loss.
How many units of electric power will be consumed by 4 motors of 0.5 HP each in 8 hours?
Which of the following is not equivalent of Watts?
- ______ is defined as the time rate at which work is done or energy is transferred.
