Suppose that the plank has a mass 15 kg, and we place 10 kg on the left side at a distance 2.00 m from the fulcrum, and a mass 20 kg on the right side at a distance 1.00 m form the fulcrum (so that the plank is balanced). What will be the force exerted by the fulcrum on the plank

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation:

f=ma newton's second law 7x8=56n

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.