# Finding the initial height of a roller-coaster [HELP]

## Homework Equations

PE = mgh
KE = $\frac{1}{2}$mv$^{2}$
W = ΔKE
W = Fd

## The Attempt at a Solution

g = 9.80m/s$^{2}$
hi = ?
hf = 20.0m

PEi + KEi = PEf + KEf

mghi = mghf

Would you then cancel the masses out? If you did, the initial height would be 20.0m. Am I right? Thanks in advance to anyone who helps.