• Support PF! Buy your school textbooks, materials and every day products Here!

Car accelerating on ramp - power of engine

270
1
1. Homework Statement

A car accelerates at 1 m/s^2 up a ramp which makes an angle of 5 degrees with the horizontal. Ignoring friction and air resistance what fraction of the power the engine puts into the car's motion goes into the car's kinetic energy?

2. Homework Equations



3. The Attempt at a Solution

I don't know how to attempt this problem I know the answer is 54% because this is a review problem for my test which is coming up, but how is power related to kinetic energy?
 

Answers and Replies

218
0
Power is energy (or work) per second.

Where is the energy from the engine going apart from into kinetic energy, KE?
 
270
1
some would have to be going into potential energy right? theres no friction or air resistance so nothing else could be taking energy
 
270
1
well I got to the correct answer I decided to measure the problem after the car had traveled 1 meter, used kinematics to find the final speed then put

KE/(KE+PE) and it worked out because the masses canceled out and i got .538 which is correct will the method always work out if there is no friction or any other forces to worry about. It seems like this isn't the correct way to do it.
 
mgb_phys
Science Advisor
Homework Helper
7,744
12
well I got to the correct answer I decided to measure the problem after the car had traveled 1 meter, used kinematics to find the final speed then put KE/(KE+PE)
That's correct, if you ignore friction conservation of energy is always correct - and is often the simplest way to do it.
 

Related Threads for: Car accelerating on ramp - power of engine

  • Last Post
Replies
17
Views
6K
Replies
4
Views
606
  • Last Post
Replies
8
Views
1K
  • Last Post
Replies
3
Views
588
  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
3
Views
2K
Replies
3
Views
1K
  • Last Post
Replies
8
Views
3K
Top