A cylindrical drum, open at the top, contains 30 liters of water. It drains out through a small opening at the bottom. 10 liters of water comes out in time t1, the next 10 liters in further time t2 and the last 10 liters in further time t3. Then,
Velocity of efflux through of water through the opening, . If 'a' be the area of opening, then rate of volume flow of water through the opening . As water is drained out of the tank, 'h' decreases and hence 'Q' decreases. Hence t1 < t2 < t3