A person does 115 J of work in throwing a 0.325 kg rock straight up into the air. How high will the rock get, assuming there is 20 J of air resistance?
From what I formulated: W = ΔPE
The answer says E1 = E2, but I think that's the exact same as the formula I used.
The Attempt at a Solution
W = ΔPE
115= mgh - 0
115 = (0.325)(9.8)h - 20
h = 42.386
It looked right in my head, but the problem is that the answer differ in the placement of the -20 J.
This is the correct answer given to me:
115 - 20 = Ep2
95 = mgh
95 = (0.325)(9.8)h
h = 29.83
30 J (Significant figured)
I don't understand why the -20 J should be placed with the work being done (the left side of the equation). I appreciate any attempt at helping me understand the reason.