Gauss's law for magnetic fields says that magnetic flux is always zero. faraday's law says that a changing magnetic flux through a closed surface is equal to the induced electric field around that surface. but if magnetic flux is always zero, how can it ever change? explain in detail.

Explanation:

Gauss's law of magnetism is given as

here it is surface integral of magnetic field in a 3 Dimensional closed loop

So in this type of 3D closed loop number of linens of magnetic field is always zero because it always forms closed loops

Now as per Faraday's law

here we have to find the closed integral of 2 D planar loop of electric field which will be equal to potential difference

So this is non zero because total number of lines through a planar loop is not essentially zero.

which statement about this sum is true? −245+2.7

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.