While sitting motionless in a 5 kg friction free wagon, an 80kg clown catches a 15 kg cannonball traveling horizontally at 20 m/s. after the cannonball is caught, at what speed do the clown, wagon, and ball move?

hello there!

your answer is a “generator”

a generator does not create energy but instead it transforms it.

it’s basically a motor working in reverse.

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.