These questions are actually pretty easy, if you really are struggling, you can do a little research
If the box is moving at constant velocity, net force must be zero, so:
F + fr = 0
fr = -F
<u>fr = -40 N</u>
Answer: D Medium B is denser than Medium A because light bends more in Medium B.
Explanation: The more the light bends the less energy it has
Average speed=total distance travelled/time
Answer:
Explanation:
E=(σ/ε0)
As noted by Dirac the field is the same no matter how far you are from the sheet. When your charge covers a conducting plane, as in your case, the field is, D/eo ,(D is charge density). Because the field inside the conductor (no matter how thin) is zero. The only time the field is, D/2eo, is when you have just a sheet of charge, by itself, not on a conducting plane."
