3. A venturimeter (see Fig. T) is used for measuring fiow of water along a pipe. The diameter of the venturi throat is two-fith the ciameter of the pipe. The inlet and throat are connected by water-filed tubes to a mercury U-tube manometer. The velocity of flow along the pipe is found to be 2.5Hm/s, where H is the manometer reading in metres of mercury. Determine the loss of head between inlet and throat of the venture when H is 0.49m. (Relative density of mercury is 13.6 ). [8 marks]