Question

A 1200 kg sports car accelerates from 0 m/s to 30 m/s in 10 s. What is the average power of the engine?

Answer 1

Answer:

3600N

Explanation:

Given: m = 1200kg, Vo = 0m/s, Vf = 30m/s, Δt = 10s

ΣF = ma

we need to find 'a' first, using the definition of 'a' we get equation:

a = (Vf-Vo)/Δt

a = (30m/s)/10s

a = 3 m/s^2

now substitute into top equation

ΣF = ma

Fengine = (1200kg)(3m/s^2)

Fengine = 3600N

Answer 2

Answer:

P = 54000 W or P = 54 kW

Explanation:

P = Work/time

W = Force * distance

first, find acceleration to find net force using kinematics.

v = vo + at

30 = 0 + a(10)

a = 3 m/s^2

Fnet = ma = 1200(3) = 3600N = Force

Next, find the distance traveled using kinematics.

∆x = vo(t) + 1/2at^2

∆x = 0(10) + 1/2(3)10^2

∆x = 150 m

Now use the force and distance you just calculated to find the work done.

W = Force*distance

W = 3600N * 150m

W = 540000

Calculate power.

P = W/t

P = 540000/10

P = 54000 W

or

P = 54 kW