推 kamikaze0415:就跟你說是用choose的嘛 04/20 03:47
→ kamikaze0415:這個問題本來沒有給定initial condition阿 04/20 03:48
推 gonghour:請問為何在8.4的時候θ=...有正負號，在這邊卻不用負號? 04/20 12:37
Chapter 8.7 Planetary Motion Kepler's Problem
(l/r^2)dr
θ(r) = ∫──────────────── + constant
√2μ[E +（k/r）-（l^2/2μr^2)]
Change variable by using u≡l/r and integral it,
I have a problem when evaluating at last term,
the following is the answer in the book:
" We can choose the point from which θ is measured so that the constant
is -π/2 "
(-l^2/μk)u + 1 -αu + 1
sin (θ+constant) = ────────── = ─────
√1+ 2El^2/μk^2 ε
where α= l^2/μk ε= √1+2El^2/μk^2
問題是 要怎麼知道-π/2 這個值呢？
最後答案是
α/r = 1 + εcosθ
感謝您的回答<(_ _)>
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 163.24.253.61