Question

What work is to be done to increase the velocity of a car from 18 km/hr to 90 km/hr if the mass of the car is 2000 kg? (class 9th)

Answer 1

u=18km/he

=18×5/18

=5m/s

v=90km/hr

=90×5/18

=25 m per second

M equals to 2000 kg

From work energy theorem it is clear that change in kinetic energy is equals to total work done.

Therefore ,

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

=1/2×2000×(625-25)

=6×10^5 J

This is answer to your question.