The speed of sound in air is about 340 meters per second. how long does it take a sound wave to travel a distance of 7800 meters

22.94 seconds, or in estimation it is 23 seconds.

7,800/340, is how you find that out and so it would take

22.94117647058824 seconds

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.

small = small current large mag large current