Question

What is the work to be done to increase the velocity of car from 30km/h to 60km/h if the mass of car is 1500kg

Answer 1

Work = Change in kinetic energy
= 0.5 m (v² - u²)
= 0.5 × 1500 kg × [(60 × 5/18 m/s)² - (30 × 5/18 m/s)²]
= 156250 joules
= 156.25 kJ

Work done is 156.25 kJ

Answer 2

Mass of the car,m= 1500kg

Initial velocity of the car = 30km/hr

= 30×1000m/60 ×60s

=8.33m/s

Similarly,the final velocity of the car,

v= 60km/hr

=16.67 m/s

Therefore,the initial kinetic energy of the car,

E(initial) = 1/2 mu^2

=1/2×1500×8.33

52041.68 J.

The final kinetic energy of the car,

E(final) = 1/2 1500×16.67

=208416.68 J.

Thus, the work done = change in kinetic energy

= E(final) - E(initial)

= 208416.68 - 52041.68

= 156375 J.