Charge of uniform density 90 nc/m3 is distributed throughout the inside of a long nonconducting cylindrical rod (radius = 2.0 cm). determine the magnitude of the potential difference of point a (2.0 cm from the axis of the rod) and point b (4.0 cm from the axis).

a.) travels faster in solids because the particles are closer together.

air is a gas water is a liquid

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.