Recent content by jl12

I'm sorry but I don't understand why they've ignored the angular momentum of the system because if it was just a point mass rotating around in a circle and we looked at the direction of angular momentum taken around a point just below the plane of the circle then wouldn't it point inwards and...

Oh ok that clears up so much thanks for your support.

Sorry to keep spamming but just to be clear so when you define dr or dx or whatever as vectors they don't depend on the limits of integration they are just always defined such that they go in the positive (or radial for dr) direction.

So when I integrate it I should replace dr with -dr. So is the dr always assumed to be positive so when I take the dot product dr is always in the radial direction?

Why is the dr vector in the opposite direction to if I'm taking it from infinity to r'. Surely ##m## is moving to the left? Btw thanks both for the quick reply both of you.

Homework Statement Hi I'm attempting to derive the gravitational potential energy of a point mass (##m##) that's moving from infinity to a point r' inside a gravitational field produced by a another mass ##M##. For simplicity I treated it as a one dimensional case. The problem I get is that the...

So when its been pointing along the axis of the spinning wheel its because they're considering the angular momentum of the spinning top rather than the angular momentum of the whole system?

Homework Statement Hi I'm having trouble with a question that's asking me to calculate the precession rate for a spinning top. The trouble that I'm having is that I don't understand how the angular momentum points along the axis of the spinning top (picture attached). When I use the formula...