Average Power delivered to Engine

  • #1

Homework Statement


A 1000 kg car, starting from rest, accelerates uniformly to 15 m/s in ten seconds. Assume air resistance is constant at 300N. What is the average power delivered by the engine?

Answers
a. 13500 W
b.18000 W
c. 23000 W
d. 27000 W

Homework Equations


Average power = work/time
work = force(x) where x is magnitude of displacement.
force= mass x acceleration


The Attempt at a Solution



the force is equal to 1000 kg x 15 m/s = 15000

I don't know how to factor in air resistance, or arrive at a final answer. The answer is A...
 

Answers and Replies

  • #2
212
0
explain how you got the force of the car again...
 
  • #3
force = mass times acceleration
1000 x 15= 15000
 
  • #4
212
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what is the units of the 15 value though
 
  • #5
ok.... i think i got it.... after getting the correct force (and units) times the displacement of x, (1800 * 75)/10.... gives the correct answer.

thanks.
 
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