315) A structure used to dam up a stream or river over which the water flows is called

316) The coefficient of discharge for an external mouthpiece depends upon

317) The highest efficiency is obtained with a channel of __________ section.

318) A vessel of 4 m³ contains an oil which weighs 30 kN. The specific weight of the oil is

319) Coefficient of discharge Cd is equal to (where C_c = Coefficient of contraction, C_v = Coefficient of velocity, and C_r = Coefficient of resistance)