Lagrange's Equations Intro, Generalized Coordinates, Constraints, Degrees of Freedom, Lecture 17

[@rahardikramadibrata8675]

Can you explain why, at 5:14, the velocity of the particle ball is l*theta? I thought the l was constrained, so the velocity should be theta only.

[@trigocuantico]

Can this be used for collisions? Maybe two balls colliding

[@Lars-nf3fv]

I dont quite understand why h was set to be -lcos(theta).

[@ProfessorRoss]

I’m guessing you mean around 5:45 . I’m measuring the height of the mass at point P with respect to the pivot point O. So when point P is below point O, the “height”will be negative. You could also think of it this way: consider the position vector of point P with respect to point O. If you take the vertical component or a vertical projection of this vector, you get -l*cos(theta)

[@arjyadebsengupta8159]

thank you sir

[@ProfessorRoss]

You're welcome. Thank you for watching. I hope it was helpful.