JEE Physics - Mechanical Properties of Fluids Viscosity

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Question - 1

By sucking through,eh a straw, a student can reduce the pressure in his lungs to 745 mm of Hg (density = 13.6 glcm3). Using the straw, he can drink water from a glass upto a maximum depth of ___________cm.

  • A 12.3
  • B 20.4
  • C 14.2
  • D 42.0

Question - 2

A hollow metal sphere of external radius 2 cm, thickness t and of relative density 2.5, just sinks in water. The value of t in centimetres is____________

  • A 236.1
  • B 102.0
  • C 320.0
  • D 0.27

Question - 3

A sphere of gold of radius 1 cm and density 19.2 g/cm3 has a concentric spherical cavity. If it floats with its whole volume just immersed in molten aluminium of density 2.4 g\m3 then volume of cavity in cubic centimetre would be ________\(\text { (Take } \pi=\frac{22}{7} \text { ) }\).

  • A 54.2
  • B 56.2
  • C 3.67
  • D 23.0

Question - 4

Water flows from a tap of diameter 1.2 cm at a rate of 2.4 x l0-5 m3 s-1. The density and coefficient of viscosity of water are 103 kg m-3 and 10-3 Pa-s respectively. The flow of water has Reynold's number of \(\frac{C}{\pi}\). Find C

  • A 8000
  • B 2300
  • C 1230
  • D 5630

Question - 5

A tiny ball of mass 100 g and density 2 g/cm3 is dropped in a tall jar of oil of density 0.8 g/cm3. When the ball acquires terminal velocity, the magnitude of the viscous force acting on it in dyne is __________.

  • A 2300
  • B 9800
  • C 4520
  • D 3254

Question - 6

Water from. a tap emerges vertically downwards with initial velocity 6 cm/s. Assuming constant pressure throughout the stream and a steady flow, the distance from the tap in cm at which the cross-sectional area of stream becomes \(\left(\frac{1}{3}\right)^{\mathrm{rd}}\) of the cross-sectional area of stream at the tap is ______________.\(\text { (Take } g=10 \mathrm{~m} / \mathrm{s}^{2} \text { ) }\).

  • A 412.3
  • B 52.3
  • C 21.03
  • D 14.4

Question - 7

The rate of flow of the liquid through the tube A of length I and radius r connected across a pressure head h be V. If two tubes B and C of same length but of radius r and \(\frac{\mathrm{r}}{2}\) ur. connected in series across the same pressure head h, the rate of flow of liquid through the combination \(\frac{\mathrm{V}}{\mathrm{x}}\) Find x.

  • A 12
  • B 23
  • C 17
  • D 42

Question - 8

When a small sphere of radius r falls from rest in a viscous liquid, heat gets produced due to viscous force. As sphere attains terminal velocity, rate of heat produced is proportional to rn. Find n.

  • A 12
  • B 8
  • C 4
  • D 5

Question - 9

A liquid is kept in a cylindrical vessel which is being rotated about a vertical axis through the centre of the circular base. If the radius of the vessel is 4 cm and angular velocity of rotation is 0.1 radls, then the difference in the heights of the liquid at the centre of the vessel and the edge in \(\mu \mathrm{m}\ is \) _______________\(\left(\right. Take \left.g=10 \mathrm{~m} / \mathrm{s}^{2}\right)\).

  • A 10.2
  • B 2.3
  • C 0.8
  • D 2.1

Question - 10

A human heart pumps 2.4 lit of blood through arteries every half a minute at a. pressure of 160 mm of mercury. Then power of human heart in watt is (Take g = l0 m/s2, density of mercury 13.6 x 103 kg/m3).

  • A 123.0
  • B 42.3
  • C 1.74
  • D 2.30
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