Question

A truck of mass 1000 kg,increases the speed from 36 km h to 72 km h. Find the increase is its kinetic energy

Answer 1

Initial speed = 36 km/h = 10 m/s

Final speed = 72 km/h = 20 m/s

Mass of the truck = 1000 kg

Increase in kinetic energy = Final kinetic energy - initial kinetic energy

Final kinetic energy = $\frac{1}{2}\times m \times v^2$

Final kinetic energy = $\frac{1}{2}\times 1000 \times 20^2$

Final kinetic energy = 200000 J

Initial kinetic energy = $\frac{1}{2}\times m \times v^2$

Initial kinetic energy = $\frac{1}{2}\times 1000 \times 10^2$

Initial kinetic energy = 50000 J

Now, increase in kinetic energy = 200000 - 50000

Increase in kinetic energy = 150000 Joules