Question

Define kinetic energy. Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 kmph? [3 MARKS]

Answer 1

Each point: 1 Mark

1. Energy which a body possesses by virtue of being in motion
2. Kinetic energy, $E_k=\frac{1}{2}m{v}^2$
Where,
Mass of car, m= 1500 kg
3. Velocity of car, $v=60kmphr=\frac{60\times 5}{18}m{s}^{-1}$ $\therefore E_k=\frac{1}{2}\times 1500\times (60\times \frac{5}{18}{)}^2=20.8\times {10}^{4}J$
Hence, $200.8\times {10}^{3}J$
$\Rightarrow$200.8 KJ of work is required to stop the car.