21. coherent, monochromatic light of wavelength 720 nm is incident on two closely-spaced, very narrow slits. the distance between the slits, the distance to the viewing screen behind the barrier, and location of the bright and dark spots have not been measured. we can conclude that light leaving the more distant slit which arrives at the 2nd dark spot relative to the central bright spot has traveled an extra distance of relative to the closer slit.
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.