Question

Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h​

Answer 1

Mass of car, m = 1500 kg

velocity, v = 60 km/h =  

Kinetic energy possessed by the car =  mv²  

⇒ KE =  

To stop the car, we have to make the KE of car 0. So the work need to be done is 204.4 kJ.

Answer 2

Mass of car, m = 1500 kg

velocity, v = 60 km/h = 60 \times \frac{5}{18}=16.67\ ms^{-1}60×

18

5

=16.67 ms

−1

Kinetic energy possessed by the car = \frac{1}{2}

2

1

mv²

⇒ KE = \frac{1}{2} \times 1500 \times 16.67^2=208416.7\ J=208.4\ kJ

2

1

×1500×16.67

2

=208416.7 J=208.4 kJ

To stop the car, we have to make the KE of car 0. So the work need to be done is 204.4 kJ.