What is the Minimum Time for Acceleration in an Auto Engine Power Problem?

[tmobilerocks]

Homework Statement

An auto manufacturer reports that the maximum power delivered by the engine of a car of mass 1230 kg is 92.4 kW. Find the minimum time in which the car could accelerate from rest to 29.1 m/s. In a test the time to do this is found to be 12.3 s. Account for the difference in this time.

Homework Equations

P = W/t
Work-KE theorem

The Attempt at a Solution

t = $\frac{W}{P}$
= $\frac{.5(1230)(29.1)^{2}}{92.4(10^{3})}$
= 5.64s

The difference in time is due to not accounting for friction force.

 

[Simon Bridge]

Well done: did you have a question about this problem?