Question

A man can lift 50 liter water to
height of 20m in 20 seconds. His
o
power is.........?​

Answer 1

Power  = 26 kW

Explanation:

50 liters of water would weigh 50 kg.

A force is a push or pull that acts upon an object as a result of that objects interactions with its surroundings

Force = mass * acceleration due to gravity

 = 50  * 10

 = 500 N

Power is the rate at which work is done.

Power = Work / time = Force + Displacement / time

  = 500 + 20 / 20

  = 520 / 20

  = 26 kJ/s or kW

Answer 2

Given:

Volume of water, V = 50 L

Height, h = 20 m

Time taken, t = 20 seconds

To Find:

The power of the man.

Calculation:

- Density of water = 1000 kg/m³ = 1 kg/L

- Mass of water = 50 × 1 = 50 Kg

- Work done is equal to the potential energy of the water.

⇒ W = P.E. = m × g × h

⇒ W = 50 × 10 × 20

⇒ W = 10000 J

- Power = Work done/Time

⇒ P = 10000/20

⇒ P = 500 W

- So, the power of the man is 500 W in the given case.