He horizontal surface on which the block slides is frictionless. the speed of the block before it touches the spring is 6.0 m/s. how fast is the block moving at the instant the spring has been compressed 15 cm? (assume k = 2.0 kn/m.)

what type of charge does it have? negative

need to see circuit to get time constant

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.