Question

Certain force acting on a 20 kg mass changes its velocity from 108 kilometre per hour to 36 kilometre per hour in 10 seconds. Calculate power

Answer 1

Answer:

800 W

Explanation:

108 kmph = 30m/s

36 kmph =10m/s

Now to find power we have to find work done,

work done here will be the change in kinetic energy

= 1/2 mv^2 - 1/2 mu^2

=1/2m(v^2- u^2)

=1/2 * 20 (100 - 900)

= -8000

(The minus sign refers to the retarding nature of force applied)

Now to find the power,

Power = work done / time

= 8000/10= 800 W or J/S (power is a scalar quantity so no direction is needed)