A box weighing 100 newtons is pushed up an inclined plane that is 5 meters long. It takes a force of 75 newtons to push it to the top, which has a length of 3 meters.

80%.

Explanation:

Question didn't state what is being looked for, but then

Weight of the box, w = 100 N.

Length of the plane, L = 5 m

Force used, = 75 N

Length pushed through, = 3 m

Looking at the stated parameters, the first thing that comes to mind is to look or calculate for the efficiency of the machine.

Tha efficiency can be gotten by using the relation

Change in energy divided by work done. This is gotten by saying

(100 * 3) / (5 * 75) =

300/ 375 = 0.8

Therefore, the efficiency of the machine has been calculated to be 80% or 0.8

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.

there are no contact forces mentioned on the list of choices that you've provided.