The math help thread

No you may not assume Fpy is zero because it is a pin that holds the mass on an axis (going through the paper).

So is my interpretation of a pin joint wrong? I'm assuming the pin joint is the thingy D in the figure. Because of its way of working, it's impossible for that thing to be affected by any vertical force from the pole. It will be cancelled by the wall on the other side. Assume no friction: That means it will fall with the force g towards the ground because no other forces affect it.

EDIT: If your textbook does the problem assuming Fpy is 0 or something to that effect, you should probably do it that way. But as a future reminder, that is not how reality works.

Keep in mind that physics always use models, not reality.

Also, for your question, I understood your triangle. I don't understand why that took me so long to understand it however, maybe I was just lazy. As I don't really know what the product of inertia is, I can't really answer your problem. I'm sorry about that.

Noah