Question

A 1200-kg car accelerates from rest to 20.5 m/s in 4.50 s. What is the average power delivered by the engine? Use the work-energy theorem to calculate for the work (in terms of kilojoules [kJ]). Show your complete solutions.

Answer 1

Step-by-step explanation:

Given:

m = 1200 kg

V₀ = 0 m/c

V = 20.5 m/s

t = 4.50 s

____________

N - ?

1)

Car acceleration:

a = (V - V₀) / t = (20.5 - 0) / 4.50 ≈ 4.56 m/s²

2)

Vehicle traction force:

F = m·a = 1200·4.56 ≈ 5 470 N

3)

Vehicle speed:

V = V₀ + a·t = 0 + 4.56·4.50 ≈ 20.5 m/s

4)

Average vehicle speed:

N = F·V / 2 = 5 470·20.5 / 2 ≈ 56 000 W