The car increased its speed from v1 = 36 km / h to v2 = 72 km / h, weighing 1000 kg. Find a perfect engine job.

Initial data: Vн (initial speed) = 36 km / h (10 m / s); Vк (final speed) = 72 km / h (20 m / s); m (mass of the vehicle in question) = 1000 kg.

The work done by the car engine will be equal to the change in its kinetic energy: A = Ek2 – Ek1 = 0.5 * m * Vk ^ 2 – 0.5 * m * Vn ^ 2 = 0.5 * m * (Vk ^ 2 – Vn ^ 2).

Calculation: A = 0.5 * 1000 * (202 – 10 ^ 2) = 150 * 10 ^ 3 J (150 kJ).

Answer: The work of the engine is 150 kJ.