A4.5-m-long wooden board with a 24-kg mass is supported in two places. one support is directly under the center of the board, and the other is at one end. what can be said about the forces exerted by the supports?

All the weight of the wooden board is bear by the support located at the centre of the rod, and the other support which is located at the end, will have no reaction force, or 0 reaction force.

Therefore the reaction at the centre support is equal to the weight of the board, while the support at the end has 0 reaction force.

The support at the middle of the board exerts an upward force that is equal to the weight of the board mg ( 24x9.81)N which is 235.44N.

The support at the other end exerts no force on the board since the board is already balanced by the middle support.

Explanation:

Detailed explanation and calculation is shown in the image below

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.