A fixed pulley is glued on the ceiling. A rope goes over it. The rope is fixed on the floor on one end. On the other end there is a weight.
I understand that the force that pulls at the wall (red) is the same as the weight. Let's assume that the red end of the rope actually goes straight down to the floor. What is the weight that pulls on the ceiling? (How strong does my glue has to be?)
If the setting was like
I understand that I would need a weight at the red end as heavy as the original weight to be in balance and that then glue would need to carry both weights.
However, in my case there is no second weight - the rope is fixed to the floor - which should not add weight, but should carry some. So I am confused how much weight/force my ceiling/glue has to deal with.
If the force pulling at the glue of the ceiling was A + B then I don't understand why the force suddenly doubles without any extra weight. The setup in picture 1 would be more stressful to the ceiling then if I glued the rope directly to the ceiling as in
That would seem rather unintuitive to me.
So, to rephrase my question: How is it that there is twice as much stress on the ceiling in picture 1 compare to picture 3?