Car accelerating on ramp - power of engine

AI Thread Summary
A car accelerates at 1 m/s² up a 5-degree ramp, and the problem involves calculating the fraction of engine power that contributes to kinetic energy, which is found to be 54%. The relationship between power and kinetic energy is clarified, emphasizing that power is energy per second. The energy from the engine is primarily divided between kinetic energy and potential energy, with no other forces like friction or air resistance affecting the outcome. The method used to derive the answer involved kinematics and the conservation of energy principle, confirming that the approach is valid in the absence of friction. This discussion highlights the importance of understanding energy distribution in mechanical systems.
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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?

Homework Equations





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?
 
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Power is energy (or work) per second.

Where is the energy from the engine going apart from into kinetic energy, KE?
 
some would have to be going into potential energy right? there's no friction or air resistance so nothing else could be taking energy
 
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.
 
physstudent1 said:
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.
 
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