Question

38) An engine develops 10 kW of power. How much time will it take to lift of mass of 20 kg to a height of 40 m(take g = 10 m/s2 )

Answer 1

Mass to be lifted = 20 kg

Height = 40 m

Acceleration due to gravity = 10 m/s^2

Power of the engine = 10 kW = 10000 Watts

Work done = mass × gravity × height

Work done = 20 × 10 × 40

Work done = 8000 Joules

Let the time taken be t.

Work done = Power × time

$time = \frac{Work }{Power}$

$time = \frac{8000}{10000}$

Time taken = 0.8 seconds