1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help deriving an equation using chain rule

  1. Sep 11, 2014 #1
    1. The problem statement, all variables and given/known data


    How does one get the r" equation from r'?

    2. Relevant equations

    r = distance
    v = r' = ds/dt
    a = r'' = dv/dt

    chain rule, dy/dt = dy/dx * dx/dt

    3. The attempt at a solution

    I can easily get to r' from r using the chain rule but how do you derive r" from r'? How do you apply the chain rule when there are 3 variables (sec theta, tan theta and theta dot)?

    Help would be appreciated.
  2. jcsd
  3. Sep 11, 2014 #2


    User Avatar
    Gold Member

    [itex] \frac{d}{dt} f(a(t),b(t),c(t))=\frac{\partial f}{\partial a}\dot a+\frac{\partial f}{\partial b} \dot b+\frac{\partial f}{\partial c} \dot c [/itex]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted