EASY
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The relative viscosity of blood remains constant between

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Important Questions on Viscosity and Surface Tension

MEDIUM
The velocity of water in a river is 18 km h-1 near the surface. If the river is 5m deep, find the shearing stress between the horizontal layers of water. The coefficient of viscosity of water=10-2 poise.
HARD
Consider a thin square plate floating on a viscous liquid in a large tank. The height h of the liquid in the tank is much less than the width of the tank. The floating plate is pulled horizontally with a constant velocity u0. Which of the following statements is (are) true?
EASY

A metal block of base area 0.20 m2 is placed on a table, as shown in figure. A liquid film of thickness 0.25 mm is inserted between the block and the table. The block is pushed by a horizontal force of 0.1 N and moves with a constant speed. If the viscosity of the liquid is 5.0×103 Pl, the speed of block is ______ ×10-3 m s-1.

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EASY
Under a constant pressure head, the rate of flow of orderly volume flow of liquid through a capillary tube is V. if the length of the capillary is doubled and the diameter of the bore is halved, the rate of flow would become
HARD

A steel ball is dropped in a viscous liquid. The distance of the steel ball from the top of the liquid is shown below. The terminal velocity of the ball is closest to

 

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MEDIUM
If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter 2π 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:
EASY
The velocity of upper layer of water in a river is 36 km h-1. Shearing stress between horizontal layers of water is 10-3 N m-2. Depth of the river is _____ m. (Co-efficient of viscosity of water is 10-2 Pa s)
HARD
Water from a pipe is coming at a rate of 100 liters 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 = 100 kg/m3, coefficient of viscosity of water =1 mPa s)
MEDIUM
The velocity of a small ball of mass M and density ρ, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is ρ2, then the viscous force acting on the ball will be:
EASY

A flat plate of area 10 cm2 is separated form a large plate by a layer of Glycerine 1 mm thick. If the coefficient of viscosity of Glycerine is 20 poise, the force required to keep the plate moving with a velocity of 1 cm s-1 is       
 

EASY
Identify the incorrect statement regarding Reynold's number Re:
MEDIUM
A solid sphere of volume V experiences a viscous force F when descending with a speed v in a liquid. If another solid sphere of volume 27 V descends with the same speed v in the same liquid, it experiences a viscous force
EASY
If p is the density and η is coefficient of viscosity of fluid which flows with a speed v in the pipe of diameter d, the correct formula for Reynolds number Re is
EASY
Oil is used for frying food materials rather than water, since oil
MEDIUM
Two capillary tubes of same length each of 50 cm but of different radii 4 mm and 2 mm are connected in series. When water flows, the pressure difference between the ends of the arrangement is P. Then the pressure difference between the ends of the first tube is
EASY
The velocity of water in a river is 18 km h-1 near the surface. If the river is 5 m deep, find the shearing stress between the horizontal layers of water. The coefficient of viscosity of water=10-2 poise.
MEDIUM
A layer of glycerine of thickness 1 mm is present between a large surface area and a surface area of 0.1 m2. With what force the small surface is to be pulled, so that it can move with a velocity of 1 ms-1? (Given that coefficient of viscosity = 0.07 kg m-1 s-1)
MEDIUM

The diagram shows a cup of tea seen from above. The tea has been stirred and is now rotating without turbulence. A graph showing the speed v with which the liquid is crossing points at a distance X from O along a radius XO would look like
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MEDIUM
Two capillary of length L and 2L and of radii R and 2R are connected in series. The net rate of flow of fluid through them will be (given rate of the flow through single capillary, X= πpR48ɳL)
EASY
SI unit of coefficient of viscosity is