A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be

• 8 cm

• 10 cm

• 4 cm

• 4 cm

Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is

• directly proportional to R but inversely proportional to v.

• directly proportional to both radius R and velocity v.

• inversely proportional to both radius R and velocity v.

• inversely proportional to both radius R and velocity v.

If two soap bubbles of different radii are connected by a tube,

• air flows from the bigger bubble to the smaller bubble till the sizes are interchanged.

• air flows from bigger bubble to the smaller bubble till the sizes are interchanged

• air flows from the smaller bubble to the bigger.

• air flows from the smaller bubble to the bigger.

A capillary tube of radius 0.5 mm is immersed in a beaker of mercury. The level inside the tube is 0.8 cm below the level in beaker and angle of contact is 120°. What is the surface tension of mercury, if the mass density of mercury is ρ = 13.6 x10³ kgm^-3 and acceleration due to gravity is g = 10 m/s² ?

• 0.225 N/m

• 0.544 N/m

• 0.285 N/m

• 0.375 N/m

15.

If a capillary tube of radius r is immersed in a liquid, then the liquid rises to a height h. The corresponding mass of liquid column is m. The mass of water that would rise in another capillary tube of twice the radius is

• 2 m

• 5 m

• 3 m

• 4 m

In a horizontal pipe of non-uniform cross-section, water flows with a velocity of 1 ms^-1 at a point where the diameter of the pipe is 20 cm. The velocity of water (in ms^-1) at a point where the diameter of the pipe is 5 cm is

• 64

• 24

• 16

• 32

A spherical ball of diameter 1 cm and density 5 x 10³ kg m^-3 is dropped gently in a large tank containing viscous liquid of density 3 x10³ kg m^-3 and coefficient of viscosity 0.1 Ns m^-2. The distance, the ball moves in 1 s after attaining terminal velocity is (g =10 ms^-2)

• $\frac{10}{9} \mathrm{m}$

• $\frac{2}{3} \mathrm{m}$

• $\frac{4}{9} \mathrm{m}$

• $\frac{4}{5} \mathrm{m}$

Two capillary tubes A and B of diameter 1 mm and 2 mm respectively are dipped vertically in a liquid. If the capillary rise in A is 6 cm, then the capillary rise in B is

• 2 cm

• 3 cm

• 4 cm

• 6 cm

After terminal velocity is reached, the acceleration of a body falling through a fluid is

• equal to g

• zero

• less than g

• greater than g

A liquid is filled upto a height of 20 min a cylindrical vessel. The speed of liquid coming out of a small hole at the bottom of the vessel is (take, g = 10ms^-2)

• 1.2 ms^-1

• 1 ms^-1

• 2 ms^-1

• 3.2 ms^-1