Friction occurs between two contacting surfaces. The coefficient of friction is very much dependent on the roughness of these surfaces. Some of the many ways in which the coefficient can be lessened or decreased are to lubricate the surface or make it shiny by eliminating the spikes which caused the roughness.
Electical energy is transformed into heat and light energy
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.
Hi, this sounds like a chemistry question:
If you wanted to separate sand from iron fillings for example, using tweezers would be a great tool to do this, depending on the size of the iron fillings.
P=M(mass)G(Gravity)H(Height)
Gravity=9.8
M=1.5 G=9.8 H=35
so multiply all
=514.5 potential energy
