# Roller-coaster conservation energy

## Homework Statement

So I am doing this roller coaster lab in my physics class and I'm having some problems.
You have to find the initial height of a hill and initial velocity; which was easy and I found this out.
PEi = PEf+KEf
m*9.8*h i = m*9.8*0.4572 + 1/2*m*(1.5m/s)^2
m's cancel
assume everything I have put in there is correct. The answer to H(i)=0.57
Even though we got this , our roller coaster using marbles does not complete this. So we had to extend the initial hill ; which is what our teacher wanted us to do. We extended it 1.1 more meters. So now it asked for the percentage to raise the starting point.
Which we did , we used the percent error but we keep getting like 64%
Help would be nice
Thanks

## The Attempt at a Solution

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Slightly confusing, I'll give it a shot.

Your initial calculations don't allow for losses so you're going to need more height.

Which you've got, OK.

So far as the "percentage to raise the starting point" goes, surely that would be how much you've increased the starting point height by?

In which case, your initial height is 0.57m. Your new height is 0.57 + 1.1 = 1.67m.

So the percentage increase is nearly 300% - it is nearly 3 times higher than the original starting point.