How Does Goldstein Derive the Kinetic Energy Equation in Classical Mechanics?

AI Thread Summary
The discussion focuses on the derivation of the kinetic energy equation in classical mechanics, specifically the relationship between the left-hand side (LHS) and right-hand side (RHS) of the equation md²r/dt² · dr/dt = d/dt (1/2 m (dr/dt)². Participants emphasize the application of the chain rule to derive the time derivative of (dr/dt)². There is confusion regarding the LHS, with one participant asserting that it should equal the RHS without further calculation. The conversation concludes with acknowledgment that further sections of Goldstein's work may present additional challenges.
bengeof
how is md^2r/dt^2 . dr/dt = d/dt (1/2 m (dr/dt)^2 )

Thank You
 
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bengeof said:
how is md^2r/dt^2 . dr/dt = d/dt (1/2 m (dr/dt)^2 )

Thank You

Chain rule.
 
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Likes Ibix
Can you work it out for me explicitly ?
 
Can you state the chain rule? Can you apply it to the time derivative of ##(dr/dt)^2##?
 
Ibix said:
Can you state the chain rule? Can you apply it to the time derivative of ##(dr/dt)^2##?

2dr/dt . . is that right ?
 
bengeof said:
I was able to work out the right hand side. But the left hand side is my problem. .

That makes no sense. The LHS is the answer to the derivative on the RHS. There's nothing to work out on the left.

bengeof said:
2dr/dt . . is that right ?

The stackexchange link I gave you is all about why that is not the answer!
 
okay Got it. Thank you so much !
 
  • #10
The rest of Goldstein may present difficulties.
 
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