NEET Physics - New - Mechanical Properties of Fluids

Question - 1

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of the water in the capillary is 5 g. Another capillary tube of radius 2 r is immersed in water. The mass of water that will rise in this tube is_____

• A $20.0 \mathrm{~g}$
• B $2.5 \mathrm{~g}$
• C $5.0 \mathrm{~g}$
• D $10.0 \mathrm{~g}$

Question - 2

A small hole of area of cross-section $2 \mathrm{~mm}^{2}$ is present near the bottom of a fully filled open tank of height 2 m. Taking $g=10 \mathrm{~m} / \mathrm{s}^{2}$, the rate of flow of water through the open hole would be nearly____

• A $8.9 \times 10^{-6} \mathrm{~m}^{3} / \mathrm{s}$
• B $2.23 \times 10^{-6} \mathrm{~m}^{3} / \mathrm{s}$
• C $6.4 \times 10^{-6} \mathrm{~m}^{3} / \mathrm{s}$
• D $12.6 \times 10^{-6} \mathrm{~m}^{3} / \mathrm{s}$

Question - 3

A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of $2.5 \times 10^{-2}$ $\mathrm{N} / \mathrm{m}$. The pressure inside the bubble equals at a point Z below the free surface of water in a container. Taking $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}$, density of water $=10^{3} \mathrm{~kg} / \mathrm{m}^{3}$, the value of $Z_{0}$ is____

• A 10 cm
• B 1 cm
• C 0.5 cm
• D 100 cm

Question - 4

Three liquids of densitites $\mathrm{r}_{1}, \mathrm{r}_{2}$ and $\mathrm{r}_{3}$ (with $\mathrm{r}_{1}>\mathrm{r}_{2}>\mathrm{r}_{3}$ ), having the same value of surface tension T, rise to the same height in three identical capillaries. The angle of contact $\mathrm{q}_{1}, \mathrm{q}_{2}$ and $\mathrm{q}_{3}$ obey____

• A $\frac{\pi}{2}>\theta_{1}>\theta_{2}>\theta_{3} \geq 0$
• B $0 \leq \theta_{1}>\theta_{2}>\theta_{3}<\frac{\pi}{2}$
• C $\frac{\pi}{2}<\theta_{1}>\theta_{2}>\theta_{3} \geq \pi$
• D $\pi>\theta_{1}>\theta_{2}>\theta_{3} \geq \frac{\pi}{2}$

Question - 5

A wind with speed $40 \mathrm{~m} / \mathrm{s}$ blows parallel to the roof of a house. The area of the roof is $250 \mathrm{~m}^{2}$. Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be $\left(\mathrm{P}_{\text {air }}=1.2 \mathrm{~kg} / \mathrm{m}^{3}\right)$____

• A 4.8×105 N,upwards
• B 2.4×105 N,upwards
• C 2.4×105 N,downwards
• D 4.8×105 N,downwards

Question - 6

A certain number of spherical drops of a liquid of radius 'r ' coalesce to form a single drop of radius ' R' and volume ' V . If ' T ' is the surface tension of the liquid, then

• A energy $=4 V T\left(\frac{1}{r}-\frac{1}{R}\right)$ is released
• B energy $=3 V T\left(\frac{1}{r}+\frac{1}{R}\right)$ is absorbed
• C energy $=3 V T\left(\frac{1}{r}-\frac{1}{R}\right)$ is released
• D energy is nèither released nor absorbed

Question - 7

A fluid is in streamline flow across a horizontal pipe of variable area of cross section. For this which of the following statements is correct?

• A The velocity is maximum at the narrowest part of the pipe and the pressure is maximum at the widest part of the pipe
• B Velocity and pressure both are maximum at the narrowest part of the pipe
• C Velocity and pressure both are maximum at the widest part of the pipe
• D The velocity is minimum at the narrowest part of the pipe and pressure is minimum at the widest part of the pipe

Question - 8

The wetability of a surface by a liquid depends primarily on

• A viscosity
• B surface tension
• C density
• D angle of contact between the surface and the liquid

Question - 9

A rectangular block of mass m and area of cross section A floats in a liquid of density r. If it is given a small vertical displacement from equilibrium it undergoes oscillation. with a time period T. Then_____

• A $T \alpha \frac{1}{\sqrt{A}}$
• B $T \times \frac{1}{\rho}$
• C $T, \alpha \frac{1}{\sqrt{m}}$
• D $T \alpha \sqrt{\mathrm{p}}$

Question - 10

The angle ofcontact between pure water and pure glass is_____

• A 0o
• B 45o
• C 90o
• D 135o