Question

A car's velocity increases from 36 km/h to 72 km/h. The car weighs 1400 kg. Calculate
the work done by the engine.​

Answer 1

Answer:

907,200 J

Explanation:

work done=kinetic energy

W=¹/₂ mv²

W=¹/₂*1400*(36)²

W=700*1296

W=907,200 J

Answer 2

solution✎

Let us first convert the velocities from

km/h to m/s

❥ 36 km/h = 36,000 m/ 3600 s = 10 m/s

❥ therefore, 72 km/h = 20 m/s

❥ final KE = 1/2 × m× v ²= 1/2 ×1400 kg

× (20 m/s)²

❥ = 700×400= 70,000 J

❥ change in KE = 280,000 J

❥ 210,000J = 210 kg

❥ the change in KE is = to the work done on the car by the engine, that is,

❥ 210 KG