The volume of a liquid flowing out per second of pipe of length l and radeius r is wrteen by a student as
`v = (pi P r ^4)/(8 eta l)` where P is the pressure difference between the two ends of the pipe and `eta` is coefficent of viscosity of the liquid having dimensional formula `ML^-1T^-1` Check whether the equation is dimensionally correct.

Glycerine flows steadily through a horizontal tube of length 1.5 m and radius 1.0 cm. If the amount of glycerine collected per second at one end is 4.0xx 10^-3 kg s^-1 , what is the pressure difference between the two ends of the tube ? (Density of glycerine = 1.3xx 10^3 kg m^-3 and viscosity of glycerine = 0.83 Pa s). [You may also like to check if the assumption of laminar flow in the tube is correct].