Roller Coaster Problem with KE and PE

AI Thread Summary
The discussion revolves around solving a physics problem related to the conservation of energy in a roller coaster scenario, focusing on kinetic energy (KE) and potential energy (PE). The user expresses uncertainty about the problem's language and whether the equation PEb + KEb = KEa + PEa is applicable. They attempt to derive the relationship between energies at different points, suggesting that the work done by gravity equals the change in kinetic energy. Clarification is sought on calculating potential energy at various points and the correct application of the work-energy principle. The conversation emphasizes understanding energy transformations in the context of roller coasters.
chris61986
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Homework Statement



https://dl.dropbox.com/u/92857534/physicsproblem.png

Note: Solving for part D and E

Homework Equations



Unsure. Langauge in the problem seems ambiguous.
Perhaps (KE + PE)b = (KE + PE)a

The Attempt at a Solution



So I think it's done this way.

From A to B and B to C, the equation would look this way:
PEb + KEb = KEa + PEa
PEa = 0, move KEb to right side, left with:
PEb = KEa - KEb
so WGH = 1/2mv'^2 - 1/2mv^2

Am I going the right way about this? If so, where do I go from here when I don't know both velocities?
Also, for parts A, B, and C, it's simply W = mgΔh, correct? I'm not used to things being easy :P
 
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Work energy rule says that the increase in kinetic energy of a body is equal to work done on it.
 
Do you think you could be a little less cryptic?
 
Work done by gravity is equal to the increase in kinetic energy of the car. The same is the loss in potential energy. W = mgΔh is correct.
In second part I think potential energy is to be calculated at different points.
 

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