Question

What is the work to be done to increase the velocity of car from 35km/h to 65km/h if the mass of car is 2000kg

Answer 1

work done = Force x displacement
but force =mass x acceleration
work done W= mass x displacement ……(1)
using V^2=u^2+2as
or, (65000/60x60)^2=(35000/60x60)^2+2a (since si unit of velocity is m/sec.square and time is second)
as=(18.05)^2-(9.72)^2
as=(325.8025 -94.4784)
as=231.324
putting the value of as in equation 1
W=m(as)
W=2000x231.324 joules
W=462.648 joules
I HOPE THIS WILL HELP YOU...

Answer 2

In first case

mass = 2000 kg

velocity = 35 km/h = 35 * 5/18 = 9.72 m/s

kinetic energy = 1/2 m v^2

                        = 1/2 (2000)(9.72)^2

                        = 1/2 (2000)(94.9784)

                        = 94478.4 J

In second case

mass = 2000 kg

velocity = 65 km/h = 65 * 5/18 = 18.05 m/s

kinetic energy = 1/2 m v^2

                       = 1/2 (2000)(18.05)^2

                       = 325802.5 J

Work done = increase in kinetic energy

                   = ( 325802.5 -  94478.4  )

                   =  231324.1 J

 

Hope this answer help u