4. If a1 and a2 are the cross-sectional areas of a tank and orifice, h the height of water level in tank above the centre of the orifice, the velocity of approach is given by
7. The initial difference between liquid levels of two identical cylindrical vessels having their area of cross-section A, is H. Flow time T from one vessel to another through an orifice having coefficient of discharge Cd and area a will be
8. The ratio of the hydraulic radius of a pipe running full to the hydraulic radius of a square section of a channel whose side is equal to the diameter of the pipe, is
10. If E1 and E2 are the specific energies at the start of back water curve and at the maximum rise of water respectively and ib and ie are the head slope and the energy line slope respectively, the length of back water (L) is given by