Mass with spring and pendulum

[@tiagosbc2009]

I believe the first resultant equation's end should be -kx, shouldn't it?

[@backbench3rs659]

in equation (2) two terms cancel out because of same value but opposites in sign ... and BTW excellent way of teaching thanks

[@aliozturk57]

You had a sign mistake in the second equation (for pendulum). Some terms could have been canceled at there!

[@ismailtageldin5435]

thank you very much for this, really appreciate the effort you put in your videos :)

[@prettyd31]

the pause at 9:57 is awesome

[@SayedMohameds]

Hello Rhett, I highly appreciate your work, It is really helpful. I have a technical question, if the whole system rotate around Z-axis, how can I update the equations of motion. If you have a reference that it might help. I would be really grateful. Thank you

[@hostkakamay2577]

Nice explanation, but I get stuck with The natural frequency of the systems

[@chaimaak9949]

what if we had an other pendulum atteched to the first one :/ HOW CAN WE FIND THE LAGRANDE ? I DID IT BUT IT WASS SO LONG

[@bckahraman]

Can someone tag me on a problem like this one solved in a book ? I am searching but I can not find an equation of motion solution of this kind of problem..

[@anirbandas6122]

Thanks,, it was very helpful

[@TrueValueResearch]

Why is it that your potential for the pendulum is not mgL(1-cos(theta))?

[@Sapien_by_chance]

guess he has made a mistake there. should be mgl(1-cos (theta)).

[@alejandromoreira9896]

IT IS CORRECT, U=0 at y2=0 , x=0 . -m2*g*L(1-cos(theta)) when U=0 at y2=-L , x=0 .

[@michaelreynolds4849]

you dropped the 2 in the original equation for T in the part 2*L*X_dot*Theta_dot*cosTheta