When does a car engine have to do a great job: when accelerating from standstill to a speed of 36 km / h

When does a car engine have to do a great job: when accelerating from standstill to a speed of 36 km / h or when the speed increases from 36 to 72 km / h? Consider the same resistance force in both cases.

These tasks: Vр1 (the first speed reached during acceleration) = 36 km / h = 10 m / s; Vр2 (second achieved speed) = 72 km / h = 20 m / s.

1) Work when accelerating to 36 km / h: A1 = ΔEk1 = m * ΔV1 ^ 2/2 = m * (Vр1 ^ 2 – 0) / 2 = m * (10 ^ 2 – 0) / 2 = 50m J.

2) Work when accelerating from 36 km / h to 72 km / h: ΔEk2 = m * ΔV2 ^ 2/2 = m * (Vр2 ^ 2 – Vр1 ^ 2) / 2 = m * (20 ^ 2 – 10 ^ 2 ) / 2 = 150m J.

Answer: A lot of work needs to be done when the speed increases from 36 km / h to 72 km / h.