Advertisements
Advertisements
प्रश्न
With increase in temperature, the viscosity of ______.
- gases decreases.
- liquids increases.
- gases increases.
- liquids decreases.
Advertisements
उत्तर
c and d
Explanation:
The viscosity of gases increases with the increase in temperature, because of the increasing temperature the rate of diffusion increases.
The viscosity of liquid decreases with the increase in temperature, because the cohesive force between the liquid molecules decreases with the increase in temperature.
Relation between the coefficient of viscosity and temperature (Andrade formula)
`η = (Ae^(Cρ/T))/(ρ^(-1/3))`
Where T = Absolute temperature of the liquid, p = density of a liquid and A and C are constants.
Important point: With the increase in temperature, the coefficient of viscosity of liquids decreases but that of gases increases. The reason is that as temperature rises, the atoms of the liquid become more mobile, whereas in the case of a gas, the collision frequency of atoms increases as their motion becomes more random.
APPEARS IN
संबंधित प्रश्न
Fill in the blanks using the word(s) from the list appended with each statement
Viscosity of gases. .. with temperature, whereas viscosity of liquids . . . with temperature (increases / decreases)
Explain why The size of the needle of a syringe controls flow rate better than the thumb pressure exerted by a doctor while administering an injection
A metal sphere of radius 1 mm and mass 50 mg falls vertically in glycerine. Find (a) the viscous force exerted by the glycerine on the sphere when the speed of the sphere is 1 cm s−1, (b) the hydrostatic force exerted by the glycerine on the sphere and (c) the terminal velocity with which the sphere will move down without acceleration. Density of glycerine = 1260 kg m−3 and its coefficient of viscosity at room temperature = 8.0 poise.
Water flows at a speed of 6 cm s−1 through a tube of radius 1 cm. Coefficient of viscosity of water at room temperature is 0.01 poise. Calculate the Reynolds number. Is it a steady flow?
Which has greater viscosity, oil or honey? Why?
A small sphere of radius 2 cm falls from rest in a viscous liquid. Heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity is proportional to
Distinguish between streamlined flow and turbulent flow.
What is Reynold’s number? Give its significance.
Derive Poiseuille’s formula for the volume of a liquid flowing per second through a pipe under streamlined flow.
Why two holes are made to empty an oil tin?
An incompressible liquid flows through a unifonn cross sectional tube with velocity 20 cm/s. If the thickness of liquid layer is 0.8 cm then velocity of gradient of flow is ____________.
From amongst the following curves, which one shows the variation of the velocity v with time t for a small-sized spherical body falling vertically in a long column of a viscous liquid.
In motors, more viscous oil is used in summer than in winter due to ____________.
Analogy
Viscous force: ______:: Buoyant force: ______.
The velocity of a small ball of mass M and density d, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is `"d"/2`, then the viscous force acting on the ball will be ______
Is viscosity a vector?
An air bubble of negligible weight having radius r rises steadily through a solution of density σ at speed v. The coefficient of viscosity of the solution is given by ______.
A spherical solid ball of volume V is made of a material of density ρ1. It is falling through a liquid of density ρ2 (ρ2 < ρ1). Assume that the liquid applies a viscous force on the ball that is proportional to the square of its speed v, i.e., `"F"_"viscous"`= -kv2 (k > 0). The terminal speed of the ball is ______.
State the formula and S.I. units of coefficient of viscosity.
A water pipe with diameter of 5.0 cm is connected to another pipe of diameter 2.5 cm. How would the speeds of the water flow compare?
