Physics Circle home Student Login

Home›Chapters›Fluid Dynamics PYQs›Types of Flow, Reynolds Number & Continuity›Question 21

JEE Main 2015 (10 Apr, Shift 1) · Types of Flow, Reynolds Number & Continuity

Types of Flow, Reynolds Number & Continuity question from JEE Main 2015 (10 Apr, Shift 1)

Q21JEE Main 2015 · 10 APR · SHIFT 1Medium

Types of Flow, Reynolds Number & Continuity

If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter 2π\frac{2}{\sqrt{\pi}} cm then the Reynolds number for the flow is (density of water = 103 kg/m3 and viscosity of water = 10−-3 Pa.s) close to:

Show answer and solution

Answer: (a)

  1. Q=15×10−35×60=5×10−5 m3/sQ = \dfrac{15\times10^{-3}}{5\times60} = 5\times10^{-5}\text{ m}^3/\text{s}
  2. r=1π cm⇒A=πr2=1 cm2=10−4 m2r = \dfrac{1}{\sqrt{\pi}}\text{ cm} \Rightarrow A = \pi r^2 = 1\text{ cm}^2 = 10^{-4}\text{ m}^2, so v=QA=0.5 m/sv = \dfrac{Q}{A} = 0.5\text{ m/s}
  3. Re=ρvDη=103×0.5×2π×10−210−3≈5.6×103R_e = \dfrac{\rho v D}{\eta} = \dfrac{10^3 \times 0.5 \times \frac{2}{\sqrt{\pi}}\times10^{-2}}{10^{-3}} \approx 5.6\times10^{3}
  4. So the answer is (a) about 55005500.
Report a mistake

More questions on Types of Flow, Reynolds Number & Continuity