Which is the best example of forces acting in the same direction?
a boy lifting his chest off the ground during a pushup
two football players pushing a tackling sled
a person pulling out a garden hose from its reel
two dogs playing tug-of-war with a rope

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

explanation:

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.