# There is a hole at the side-bottom of a big water tank. The area of the hole is 4mm2. …

Q: There is a hole at the side-bottom of a big water tank. The area of the hole is 4mm2. Through it a pipe is connected. The upper surface of water is 5 m above the hole. The rate of flow of water through the pipe is (in m³s-1) (g = 10 ms-2)

(a) 4 × 10-5

(b) 4 × 105

(c) 4 × 10-6

(d) 28 × 10-5

Ans: (a)

Sol:

Velocity of efflux is

$\displaystyle v = \sqrt{2 g h}$

$\displaystyle = \sqrt{2 \times 10 \times 5} = 10 m/s$

Rate of flow

$\displaystyle = A v = 4 \times 10^{-6}\times 10$

= 4 × 10-5