Work/Power!?

Question

A 1000 kg car moving at 4.0 m/s increases its speed to 12 m/s in 6.0 seconds. a) What is the force of the engine accelerating the car? b) What is the work done by the engine in accelerating the car? c) What is the power output of the engine during this acceleration? 

Answer 1

acceleration = a = Δv/Δt = (12–4)/6 = 4/3 m/s²

F = ma = (4/3)(1000) = 4000/3 N

v² = v₀² + 2ad

12² = 4² + 2(4/3)d

(8/3)d = 144 – 16 = 128

d = 48 m

work = Fd = (4000/3)48 = 64000 J

power = work/time = 64000/6 = 10700 watts