Question

An engine develops 10kW of power how much time will it take to lift a mass of 200 kg to a height of 40m

Answer 1

We know that energy = power * time.
Ie the potential energy for the mass of 200kg to be lifted to 40m is provided by the engine.
Hence, energy from engine=potential energy.
P*t=P. E
P=Power=10kw=10000w.
t=time.
P. E=Potential energy=mgh.
m=mass. g=gravitational constant=9.8m/sq.sec.
h=height.
$10000 \times t = 200 \times 9.8 \times 40$
$t = \frac{200 \times 9.8 \times 40}{10000}$
$t = 7.84secs$

Answer 2

Time taken by the engine to lift the mass is 8s.