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.
Answer:1.084
Explanation:
Given
mass of Pendulum M=10 kg
mass of bullet m=5.5 gm
velocity of bullet u
After collision let say velocity is v
conserving momentum we get
Conserving Energy for Pendulum
Kinetic Energy=Potential Energy
here 
from diagram
therefore
initial velocity in terms of v
For first case 
for second case 
Therefore 
i.e.
Passes the the law then through the people where it is followed
Maintain their positions.
Solids are incompressible, just like liquids. The electrostatic forces between the atoms of block and the atoms of table prevent the two objects from moving into one another.
