A snowboarder starting at rest comes down a slope at an angle of 30 degrees with the horizontal. The skier makes a total vertical descent of 100 m and then coasts along a level section which runs for 400m before entering the beginner's area.

(1) How large must the coefficient of friction be to just prevent the aggressive snowboarder from entering the learning area, and wreaking havoc?

(2) Using the coefficient of friction found in (1) what is the maximum velocity that can be attained by the snowboarder?

Which quantity is equivalent to the product of the absolute index of refraction of water and the speed of light in water?

(1) frequency of light in water
(2) sine of the angle of incidence
(3) speed of light in a vacuum
(4) wavelength of light in a vacuum