The refractive index of a material is a dimensionless number that describes how fast light travels through the material. It is defined as n={\frac {c}{v}}, where c is the speed of light in vacuum and v is the phase velocity of light in the medium.
the ratio of the velocity of light in a vacuum to its velocity in a specified medium.
<span>Submarines are equipped with water tanks called ballast tanks that fill up to submerge the vessel. Emptying the tanks and filling them with air causes the submarine to surface.</span>
The ability to reproduce is essential for a species, but not for an individual. There are some people that can't reproduce, but they're still alive!
Answer:
fo = 378.52Hz
Explanation:
Using Doppler effect formula:

where
f' = 392 Hz
C = 340m/s
Vb = 20m/s
Va = 31m/s
Replacing these values and solving for fo:
fo = 378.52Hz
Answer:
Directly proportional: as one amount increases another amount increases at the ... The "constant of proportionality" is the value that relates the two amounts ... Example: y is directly proportional to x, and when x=3 then y=15. ... Speed and travel time are Inversely Proportional because the faster we go the shorter the time.