Verified Solution • 2025–26 Session moderate

QJEEM19Pha75f: JEE Main 2019 Physics - Class 11 JEEM19Pha75f Solution: Water from a pipe is coming at a rate of 100 litres per minute. …

Water from a pipe is coming at a rate of 100 litres per minute. If the radius of the pipe is 5 cm, the Reynolds number for the flow is of the order of : (density of water = 1000 kg/m3, coefficient of viscosity of water = 1mPas)

Multiple Choice Options

  • A 106
  • B 104
  • C 103
  • D 102

Step-by-Step Verified Solution

Flow rate of water (Q) = 100 lit/min

= 100×10−360=53×10−3m3

∴ Velocity of flow (v)

= QA=5×10−33×π×(5×10−2)2

=1015π=23πm/s

= 0.2 m/s

∴ Reynold number (Re) = Dvρη

=(10×10−2)×23π×10001=2×104

∴ Order of Re = 104

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