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QJEEM20Ph5013: JEE Main 2020 Physics - Class 11 JEEM20Ph5013 Solution: Water flows in a horizontal tube (see figure). The pressure of…

Water flows in a horizontal tube (see figure).
The pressure of water changes by 700 Nm–2
between A and B where the area of cross section
are 40 cm2 and 20 cm2, respectively. Find the
rate of flow of water through the tube.
(density of water = 1000 kgm–3) JEE Main 2020 (Online) 9th January Morning Slot Physics - Properties of Matter Question 199 English

Multiple Choice Options

  • A 1810 cm3/s
  • B 2420 cm3/s
  • C 3020 cm3/s
  • D 2720 cm3/s

Step-by-Step Verified Solution

Rate of flow of water is same at both A and B

AAVA = ABVB

(40)VA = (20)VB

VB = 2VA .......(1)

Using Bernoulli's theorem

PA + 12ρVA2 = PB + 12ρVB2

⇒ PA - PB = 12ρVB2 - 12ρVA2

⇒ 700 = 12×1000(4VA2−VA2)

⇒ VA = 0.68 m/s = 68 cm/s

∴ Flow rate = AAVA = (40)(68) = 2720 cm3/s

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