Answer:
When you don't move, you still use energy. This energy is called potential energy, or, stored energy.
When you don't move or do work, you can use energy.
<span>The mechanical energy is conserved.
I hope this helps, good luck! :)</span>
Answer:
Differences can be :
1. Lever is onr of the six simple machines but pulley is a simple machine which has a wheel and axle .
2. Lever is of 3 types (first class , second class , third class ) but pulley is of only 2 types
I hope this helps you
Light that enters the new medium <em>perpendicular to the surface</em> keeps sailing straight through the new medium unrefracted (in the same direction).
Perpendicular to the surface is the "normal" to the surface. So the angle of incidence (angle between the laser and the normal) is zero, and the law of refraction (just like the law of reflection) predicts an angle of zero between the normal and the refracted (or the reflected) beam.
Moral of the story: If you want your laser to keep going in the same direction after it enters the water, or to bounce back in the same direction it came from when it hits the mirror, then shoot it <em>straight on</em> to the surface, perpendicular to it.
