- #1
nhmllr
- 185
- 1
I was watching something on elliptical orbits. Early on, I saw something that really bugged me and I can't continue until I figure out what it's about:
Mechanical Energy = Kinetic Energy + Potential Energy
I know that KE = 1/2*mv^2, which makes sense and I know why
I know that PE = mgh = mMG/r, which makes sense and I know why
So why did the lecturer write
ME = 1/2*mv^2 - mMG/r
?
Shouldn't it be a +?
Mechanical Energy = Kinetic Energy + Potential Energy
I know that KE = 1/2*mv^2, which makes sense and I know why
I know that PE = mgh = mMG/r, which makes sense and I know why
So why did the lecturer write
ME = 1/2*mv^2 - mMG/r
?
Shouldn't it be a +?