Answer:
a
because the mechanical wave is when it goes over and over again
The noise and vibration could affect your body and mood in many ways while operating a boat. The noise and vibration could make you moody or uncomfortable, because it will also distract you in doing what you're supposed to do. Your body will also be affected, making your body tired because of the things surrounding you and the noise and vibration, it could affect your body in many ways.
What are your answer choices?
Turn lights off, unplug electronics, and use solar 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.
