Potential Grav. Energy to Kine. Energy Problem

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The discussion revolves around calculating the energy lost due to friction on a roller coaster between two peaks. The total mass of the cart is 280 kg, with peak K at 46.0 m and peak L at 21.5 m. The kinetic energy (KE) and potential energy (PE) at both peaks are compared to determine energy loss. The user initially struggled with the calculations but ultimately found that comparing total energy at both points yielded the correct result of 85,000 J. The conversation emphasizes the importance of using both kinetic and potential energy in energy loss calculations.
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Homework Statement


On a roller coaster ride the total mass of the cart - with passengers included - is 280 kg. Peak K is at 46.0 m above the ground, peak L is at 21.5 m. The speed of the cart at K is 17.1 m/s, at L it is 12.8 m/s. How much energy is lost due to friction between the two peaks?


Homework Equations


Ke = 1/2mv^2 = mgh


The Attempt at a Solution


I tried finding the Ke at the 2 different points and subtracting.. it didn't work .
then i tried with the mgh and subtracted it, and it still didn't work.
So i guess I'm confused on which of the given data i should use.

Thanks alot!
 
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Compare the total energy (KE + PE) at the two points.
 
i see. I got 85000, which was right.
Thanks again
 
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