What is the Relationship Between Energy and Friction on an Inclined Plane?

AI Thread Summary
The discussion revolves around calculating the average force of friction for a 750kg car coasting up a 2.5-degree incline to a height of 22m. The user initially struggled with the problem but ultimately derived a solution using energy principles, equating the initial kinetic energy minus the final potential energy to the energy lost to friction. They formulated the relationship by expressing the friction force as the difference between initial kinetic energy and final potential energy divided by the distance traveled along the incline. The user also noted the importance of including friction in their calculations to accurately determine the force. This approach highlights the interplay between energy and friction on an inclined plane.
slaw155
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Homework Statement


EDIT: I have solved it entirely myself.

Homework Equations


The Attempt at a Solution

 
Last edited:
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slaw155 said:

Homework Statement


A 750kg mass car with initial speed 110km/h coasts up a slope inclined at 2.5degrees to the horizontal to a height of 22m above its starting point. What is the average force of friction?


Homework Equations



No real clue about this one

The Attempt at a Solution



As above, I don't really have an idea on how to do this. I've drawn a force vector diagram and considered energy but can't seem to work it out.
Even so, you are required to post your attempt, so far as it goes.
 
haruspex said:
Even so, you are required to post your attempt, so far as it goes.

I have worked it out entirely using my own self-determined methods.
 
Last edited:
Without friction the initial KE should equal the final PE.
 
With friction, final PE should equal initial KE minus energy lost to friction- the friction force times the distance traveled.
 
So :

The initial KE - the final PE = the energy lost to friction
= ( ½ * m * v ² ) - ( m * g * h )
( Joules )

Over the length of the incline, the energy lost to friction = ( constant ) friction force * distance travelled
( the length of the incline = 22.0 / ( sine 2.5 ° ) )

So, then, the friction force must equal ( ( initial KE ) - ( final PE ) ) / distance travelled

Comments please.
 

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