If the light strikes the plastic (from the water) at an angle θw, at what angle θa does it emerge from the plastic (into the air)? express your answer in terms of nw, np, na, and θw. remember that the inverse sine of a number x should be entered as asin(x) in the answer box.

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.