Answer:
The speed of light measured in any frame is c = 3.00E8 m/s.
This is one of Einstein's postulates of special relativity.
Answer:Zero
Explanation:
Given child moves the box with constant velocity over his head .
Force acting on box due to gravity is equal to his weight
Displacement of the box is Perpendicular to the direction of Applied force
Work done is given by


here
is the angle between Force and displacement which is 
so work done is zero
Answer:
The energy lost by the atoms is given off as an electromagnetic wave. ... even if it's not very intense, will always cause electrons to be emitted.
Explanation:
You measure the distance between crest and crest or trough and trough