A uniform circular disc of moment of inertia 0.2 kgm^2 and radius 0.15m is mounted on a horizontal cylindrical axle of radius 0.015m and negligible mass. Neglecting frictional loses in the bearing calculate, the angular velocity acquired from rest by the application for 24 seconds of a force of 20N tangential to the axle​

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.

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this