An athlete whose mass is 90.0 kg is performing weight-lifting exercises. Starting from therest position, he lifts, with constant acceleration, a barbell thatweighs 490 N. He lifts the barbell a distance of 0.60 m in a time of 1.6 s.
a) Draw a clearly labeled free-body force diagram for thebarbell and for the athlete.
b) Use Newton's laws to find the total force that his feetexert on the ground as he lifts the barbell. ( Please show all work).

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.