Question

Calculate the work required to be done to stop a car of 1200kg moving at a speed of 54km/h

Answer 1

mass = 1200kg
velocity = 54km/hr= 15m/s
kinetic energy = 1/2mv2
=1/2 ×1200×(15)2
=135000 joule

here work done is in the form of kinetic energy so work done =135000joules

hope it helps...

Answer 2

54 km/hr = 54 x 1000/60 x 60 m/s=15m/s
work done
= kinetic energy
=1/2 mv^2
= (1/2 x 1200 x 15 x 15)J
=( 225 x 600)J
=135000 J