- #1
jeffbarrington
- 24
- 1
Homework Statement
Hi, I have this problem:
For motion under a pure (rest mass preserving) inverse square law force f = −αr/r3 , where α is a constant, derive the energy equation γmc2 − α/r = constant.
Homework Equations
E = γmc2
dE/dt = f.u for a pure force
The Attempt at a Solution
I start by saying:
dE/dt = f.u = f.dr/dt
Next, I know f is independent of time, so I can just integrate this to get:
E = f.r +constant
So then you get:
γmc2 = -α/r + constant
Which is painfully close to the result I'm meant to get but out by a minus sign. I don't know if I've made an error here or if the question is erroneous.
Thanks for any help.