I'm stuck on the following question:
ABCD is a uniform square lamina with side 4 and mass 8kg. It's hinged at A so that it is free to move in the vertical plane. It is mantained in equilibrium with B vertically below A by a horizontal force acting at C and a vertical force acting at D, each of magnitude F newtons. Find the value of F.
I don't know how to resolve the forces when taking moments at A or if they even need to be resolved since a square has 90 degrees so the forces are penpendicular to the side AB. Can someone help please?
The left turning momentum is caused by the forces and and the effective lever arm l.
The length of
and since the resulting force of and is :
Because is perpendicular to l you don't have to take any angle into account. The solid is in equilibrium if both momenti are equal: