Advertisements
Advertisements
Question
With increase in temperature, the viscosity of ______.
- gases decreases.
- liquids increases.
- gases increases.
- liquids decreases.
Solution
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
RELATED QUESTIONS
A raindrop falls near the surface of the earth with almost uniform velocity because
A spherical ball is dropped in a long column of a viscous liquid. The speed of the ball as a function of time may be best represented by the graph
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?
Define the coefficient of viscosity of a liquid.
The velocity of a small ball of mass 0.3 g and density 8 g/cc when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is 1.3 g/cc, then the value of viscous force acting on the ball will be x × 10-4 N, and the value of x is ______.
[use g = 10 m/s2]
The coefficient of apparent expansion of mercury in a glass vessel is 153 × 10-6/°C and in a steel vessel is 144 × 10-6/°C. If α for steel is 12 × 10-6/°C, then that of glass is ______.
A liquid of density ρ and coefficient of viscosity η flows with velocity v through a tube of diameter D. A quantity `"R" = (rho"vD")/η`, determines whether the flow will be streamlined or turbulent. R has the dimension of ______.
Define the coefficient of viscosity.
The dimensions of coefficient of viscosity are ______.
