Question

What work is done to increase the velocity of car from 18 km/hr to 90km/hr .if the mass of car is 2000kg

Answer 1

Initial v.= 18km/hr= 5 m/s

Final v.= 90km/hr= 25m/s

Work done = kinetic energy

K.e= 1/2 m(v^2 -u^2)

= 1/2×2000(25^2-5^2)

=1000(625-25)

=600000 J

Hope it will help!!

Answer 2

Given,

Mass of the car=2000kg,

Initial velocity=18km/hr

final velocity=90km/hr

To Find,

Work done to increase the velocity.

Solution,

Initial velocity,

u = 18km/hr= 5 m/s

Final velocity,

v= 90km/hr= 25m/s

We know that, Work done = change in kinetic energy

Work done = 1/2 m(v² -u²)

                   = 1/2×2000(25²-5²)

                   =1000(625-25)

                   =600000 J

We know, 1kJ=1000J

               ⇒1J=1/1000kJ

               ⇒600000J=600000/1000kJ

                                    =600kJ

Hence, Work done to increase the velocity is 600kJ.