If the ratio of numbers of turns in secondary to primary coil is 1:4. calculate teh secondary voltage where primary voltage is 220v

Ns/Np=1/4

Vs=?

Vp=220V

Ns/Np=Vs/Vp

Vs=Ns/NpxVp=1/4x220=55V

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.