how can I measure the power?

Question

A sled is being pulled along a horizontal surface by a horizontal force of magnitude 600 N. Starting from rest, the sled speeds up with acceleration 0.08 for 1 minute.

Part E
Find the average power created by force .
Express your answer in watts to three significant figures.

Answer 1

Hi googoosh g

The average power (P) is equal to the work (W) done divided by the time (t) over which it was done:

P = W/t

The work done is equal to the integral of the force wrt to distance(s):

W = int|F.ds

For a constant force, this reduces to W = F*s, so

P = F*s/t

We know F and t, we need to discover s, the ditance over which the force was applied. To find s we use kinematics:

s = ut + 1/2at^2

u = initial velocity = 0, a = acceleration = 0.08m/s/s, t = time = 60s:

s = 0 + 1/2*0.08*(60)^2

s = 144m

So now:

P = F*s / t

P = 600N * 144m / 60s

P = 1440W, = 1.44*10^3W (to 3 sig figs)


Hope this helps!
The Chicken