A city located on the coast of North America has warmer winters and cooler summers than a city at the same elevation and latitud
e located near the center of North America. Which statement best explains the difference between the cities' climates? A) Wind speeds are usually greater over land surfaces than over ocean surfaces.
B) Ocean surfaces have a lower specific heat than land surfaces.
C) Warm, moist air raised when it meets cool, dry air.
D) Ocean surfaces change temperature more slowly than land surfaces.
I don't like any of those choices. But if you absolutely have to pick your answer from this list, then it has to be 'D'.
The ocean is an enormous storage vessel for heat. It gets heat from the air in the Summer ... which somewhat cools places near the coast ... and it releases heat into the air during the Winter ... which warms places near the coast.
So I guess it's true that ocean surfaces change temperature more slowly than land surfaces do, and they influence the land nearby in the process. But this ignores the reason for the slow changes in ocean surface temperature. It's a lot like saying that the loud noise produced by a race car is the result of the car's ability to appear in a far different location after a short time.
Among those two medium, light would travel faster in the one with a reflection angle of (when light enters from the air.)
Explanation:
Let denote the speed of light in the first medium. Let denote the speed of light in the air. Assume that the light entered the boundary at an angle of to the normal and exited with an angle of . By Snell's Law, the sine of and would be proportional to the speed of light in the corresponding medium. In other words:
.
When light enters a boundary at the critical angle , total internal reflection would happen. It would appear as if the angle of refraction is now . (in this case, .)
Substitute this value into the Snell's Law equation:
.
Rearrange to obtain an expression for the speed of light in the first medium:
.
The speed of light in a medium (with the speed of light slower than that in the air) would be proportional to the critical angle at the boundary between this medium and the air.
For , is monotonically increasing with respect to . In other words, for in that range, the value of increases as the value of increases.
Therefore, compared to the medium in this question with , the medium with the larger critical angle would have a larger . such that light would travel faster in that medium.