If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter 2/√π cm then the Reynolds number for the flow is (density of water = 10^{3} kg/m^{3} and viscosity of water = 10^{-3} Pa.s) close to:

- 5500
- 11,000
- 550
- 1100

**Solution**

Reynolds number is given by

R = ρvd/η

The volume of the water flowing out per second is

Q = v × πd^{2}/4

v = 4Q/d^{2}π

R = ρvd/η

R = 4ρQ/πdη

ρ = Density of water = 10^{3} kg/m^{3}

Q = 3 L / min = 3 × 10^{-3} / 60 = 5 × 10^{-5} m^{3}/s

d = 2/√π × 10^{-2} m = 1.125 × 10^{-2} m

η = Viscosity = 10^{-3} Pa.s

So, R = (4 × 10^{3} × 5 × 10^{-5})/(3.14 × 1.125 × 10^{-2} × 10^{-3})

R ≅ 5500

**The correct option is A.**