03. Excess of Pressure (Bubbles and Drops)
Mechanical Properties of Fluids

143101 In a cylinder provided with a pistion, air is under pressure $P_{1}$ at a constant temperature ' $t$ '. $A$ soap bubble with radius ' $r$ ' and surface tension ' $T$ ' is lying inside the cylinder. To reduce the radius of the soap bubble to half, the required air pressure inside the cylinder is

1 $8 \mathrm{P}_{1}+\frac{24 \mathrm{~T}}{\mathrm{r}}$
2 $8 \mathrm{P}_{1}+\frac{3 \mathrm{~T}}{\mathrm{r}}$
3 $8 \mathrm{P}_{1}+\frac{2 \mathrm{~T}}{\mathrm{r}}$
4 $8 \mathrm{P}_{1}+\frac{12 \mathrm{~T}}{\mathrm{r}}$
Mechanical Properties of Fluids

143102 A soap bubble has radius ' $R$ ' and thickness $\mathrm{d}( \lt \lt \mathrm{R})$. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is

1 $\left(\frac{\mathrm{R}}{3 \mathrm{~d}}\right)^{\frac{1}{3}}$
2 $\left(\frac{\mathrm{R}}{8 \mathrm{~d}}\right)^{\frac{1}{3}}$
3 $\left(\frac{\mathrm{R}}{6 \mathrm{~d}}\right)^{\frac{1}{3}}$
4 $\left(\frac{\mathrm{R}}{24 \mathrm{~d}}\right)^{\frac{1}{3}}$
Mechanical Properties of Fluids

143103 In S.I. system, the total energy of the free surface of a liquid drop is $2 \pi$ times the surface tension of the liquid .The diameter of the drop is

1 $\sqrt{3} \mathrm{~m}$
2 $\sqrt{2} \mathrm{~m}$
3 $\sqrt{5} \mathrm{~m}$
4 $\sqrt{7} \mathrm{~m}$
Mechanical Properties of Fluids

143104 A $31.4 \mathrm{~kg}$ girl wearing high heel shoes balances her weight on a single heel. The diameter of the heel is $1 \mathrm{~cm}$. The pressure (in pascal) exerted by the heel on the floor is (Take $g=10 \mathrm{~m} / \mathrm{s}^{2}$ )

1 $2 \times 10^{6}$
2 $4 \times 10^{6}$
3 $6 \times 10^{6}$
4 $8 \times 10^{6}$
Mechanical Properties of Fluids

143105 A soap bubble of radius $r$ is blown further to increase its radius to $2 r$ under isothermal conditions. If $\sigma$ is the surface tension of the soap solution, the energy spent in doing so is

1 $4 \pi \sigma r^{2}$
2 $8 \pi \sigma r^{2}$
3 $12 \pi \sigma r^{2}$
4 $24 \pi \sigma r^{2}$
Mechanical Properties of Fluids

143101 In a cylinder provided with a pistion, air is under pressure $P_{1}$ at a constant temperature ' $t$ '. $A$ soap bubble with radius ' $r$ ' and surface tension ' $T$ ' is lying inside the cylinder. To reduce the radius of the soap bubble to half, the required air pressure inside the cylinder is

1 $8 \mathrm{P}_{1}+\frac{24 \mathrm{~T}}{\mathrm{r}}$
2 $8 \mathrm{P}_{1}+\frac{3 \mathrm{~T}}{\mathrm{r}}$
3 $8 \mathrm{P}_{1}+\frac{2 \mathrm{~T}}{\mathrm{r}}$
4 $8 \mathrm{P}_{1}+\frac{12 \mathrm{~T}}{\mathrm{r}}$
Mechanical Properties of Fluids

143102 A soap bubble has radius ' $R$ ' and thickness $\mathrm{d}( \lt \lt \mathrm{R})$. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is

1 $\left(\frac{\mathrm{R}}{3 \mathrm{~d}}\right)^{\frac{1}{3}}$
2 $\left(\frac{\mathrm{R}}{8 \mathrm{~d}}\right)^{\frac{1}{3}}$
3 $\left(\frac{\mathrm{R}}{6 \mathrm{~d}}\right)^{\frac{1}{3}}$
4 $\left(\frac{\mathrm{R}}{24 \mathrm{~d}}\right)^{\frac{1}{3}}$
Mechanical Properties of Fluids

143103 In S.I. system, the total energy of the free surface of a liquid drop is $2 \pi$ times the surface tension of the liquid .The diameter of the drop is

1 $\sqrt{3} \mathrm{~m}$
2 $\sqrt{2} \mathrm{~m}$
3 $\sqrt{5} \mathrm{~m}$
4 $\sqrt{7} \mathrm{~m}$
Mechanical Properties of Fluids

143104 A $31.4 \mathrm{~kg}$ girl wearing high heel shoes balances her weight on a single heel. The diameter of the heel is $1 \mathrm{~cm}$. The pressure (in pascal) exerted by the heel on the floor is (Take $g=10 \mathrm{~m} / \mathrm{s}^{2}$ )

1 $2 \times 10^{6}$
2 $4 \times 10^{6}$
3 $6 \times 10^{6}$
4 $8 \times 10^{6}$
Mechanical Properties of Fluids

143105 A soap bubble of radius $r$ is blown further to increase its radius to $2 r$ under isothermal conditions. If $\sigma$ is the surface tension of the soap solution, the energy spent in doing so is

1 $4 \pi \sigma r^{2}$
2 $8 \pi \sigma r^{2}$
3 $12 \pi \sigma r^{2}$
4 $24 \pi \sigma r^{2}$
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Mechanical Properties of Fluids

143101 In a cylinder provided with a pistion, air is under pressure $P_{1}$ at a constant temperature ' $t$ '. $A$ soap bubble with radius ' $r$ ' and surface tension ' $T$ ' is lying inside the cylinder. To reduce the radius of the soap bubble to half, the required air pressure inside the cylinder is

1 $8 \mathrm{P}_{1}+\frac{24 \mathrm{~T}}{\mathrm{r}}$
2 $8 \mathrm{P}_{1}+\frac{3 \mathrm{~T}}{\mathrm{r}}$
3 $8 \mathrm{P}_{1}+\frac{2 \mathrm{~T}}{\mathrm{r}}$
4 $8 \mathrm{P}_{1}+\frac{12 \mathrm{~T}}{\mathrm{r}}$
Mechanical Properties of Fluids

143102 A soap bubble has radius ' $R$ ' and thickness $\mathrm{d}( \lt \lt \mathrm{R})$. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is

1 $\left(\frac{\mathrm{R}}{3 \mathrm{~d}}\right)^{\frac{1}{3}}$
2 $\left(\frac{\mathrm{R}}{8 \mathrm{~d}}\right)^{\frac{1}{3}}$
3 $\left(\frac{\mathrm{R}}{6 \mathrm{~d}}\right)^{\frac{1}{3}}$
4 $\left(\frac{\mathrm{R}}{24 \mathrm{~d}}\right)^{\frac{1}{3}}$
Mechanical Properties of Fluids

143103 In S.I. system, the total energy of the free surface of a liquid drop is $2 \pi$ times the surface tension of the liquid .The diameter of the drop is

1 $\sqrt{3} \mathrm{~m}$
2 $\sqrt{2} \mathrm{~m}$
3 $\sqrt{5} \mathrm{~m}$
4 $\sqrt{7} \mathrm{~m}$
Mechanical Properties of Fluids

143104 A $31.4 \mathrm{~kg}$ girl wearing high heel shoes balances her weight on a single heel. The diameter of the heel is $1 \mathrm{~cm}$. The pressure (in pascal) exerted by the heel on the floor is (Take $g=10 \mathrm{~m} / \mathrm{s}^{2}$ )

1 $2 \times 10^{6}$
2 $4 \times 10^{6}$
3 $6 \times 10^{6}$
4 $8 \times 10^{6}$
Mechanical Properties of Fluids

143105 A soap bubble of radius $r$ is blown further to increase its radius to $2 r$ under isothermal conditions. If $\sigma$ is the surface tension of the soap solution, the energy spent in doing so is

1 $4 \pi \sigma r^{2}$
2 $8 \pi \sigma r^{2}$
3 $12 \pi \sigma r^{2}$
4 $24 \pi \sigma r^{2}$
Mechanical Properties of Fluids

143101 In a cylinder provided with a pistion, air is under pressure $P_{1}$ at a constant temperature ' $t$ '. $A$ soap bubble with radius ' $r$ ' and surface tension ' $T$ ' is lying inside the cylinder. To reduce the radius of the soap bubble to half, the required air pressure inside the cylinder is

1 $8 \mathrm{P}_{1}+\frac{24 \mathrm{~T}}{\mathrm{r}}$
2 $8 \mathrm{P}_{1}+\frac{3 \mathrm{~T}}{\mathrm{r}}$
3 $8 \mathrm{P}_{1}+\frac{2 \mathrm{~T}}{\mathrm{r}}$
4 $8 \mathrm{P}_{1}+\frac{12 \mathrm{~T}}{\mathrm{r}}$
Mechanical Properties of Fluids

143102 A soap bubble has radius ' $R$ ' and thickness $\mathrm{d}( \lt \lt \mathrm{R})$. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is

1 $\left(\frac{\mathrm{R}}{3 \mathrm{~d}}\right)^{\frac{1}{3}}$
2 $\left(\frac{\mathrm{R}}{8 \mathrm{~d}}\right)^{\frac{1}{3}}$
3 $\left(\frac{\mathrm{R}}{6 \mathrm{~d}}\right)^{\frac{1}{3}}$
4 $\left(\frac{\mathrm{R}}{24 \mathrm{~d}}\right)^{\frac{1}{3}}$
Mechanical Properties of Fluids

143103 In S.I. system, the total energy of the free surface of a liquid drop is $2 \pi$ times the surface tension of the liquid .The diameter of the drop is

1 $\sqrt{3} \mathrm{~m}$
2 $\sqrt{2} \mathrm{~m}$
3 $\sqrt{5} \mathrm{~m}$
4 $\sqrt{7} \mathrm{~m}$
Mechanical Properties of Fluids

143104 A $31.4 \mathrm{~kg}$ girl wearing high heel shoes balances her weight on a single heel. The diameter of the heel is $1 \mathrm{~cm}$. The pressure (in pascal) exerted by the heel on the floor is (Take $g=10 \mathrm{~m} / \mathrm{s}^{2}$ )

1 $2 \times 10^{6}$
2 $4 \times 10^{6}$
3 $6 \times 10^{6}$
4 $8 \times 10^{6}$
Mechanical Properties of Fluids

143105 A soap bubble of radius $r$ is blown further to increase its radius to $2 r$ under isothermal conditions. If $\sigma$ is the surface tension of the soap solution, the energy spent in doing so is

1 $4 \pi \sigma r^{2}$
2 $8 \pi \sigma r^{2}$
3 $12 \pi \sigma r^{2}$
4 $24 \pi \sigma r^{2}$
Mechanical Properties of Fluids

143101 In a cylinder provided with a pistion, air is under pressure $P_{1}$ at a constant temperature ' $t$ '. $A$ soap bubble with radius ' $r$ ' and surface tension ' $T$ ' is lying inside the cylinder. To reduce the radius of the soap bubble to half, the required air pressure inside the cylinder is

1 $8 \mathrm{P}_{1}+\frac{24 \mathrm{~T}}{\mathrm{r}}$
2 $8 \mathrm{P}_{1}+\frac{3 \mathrm{~T}}{\mathrm{r}}$
3 $8 \mathrm{P}_{1}+\frac{2 \mathrm{~T}}{\mathrm{r}}$
4 $8 \mathrm{P}_{1}+\frac{12 \mathrm{~T}}{\mathrm{r}}$
Mechanical Properties of Fluids

143102 A soap bubble has radius ' $R$ ' and thickness $\mathrm{d}( \lt \lt \mathrm{R})$. It collapses into a spherical drop. The ratio of excess pressure in the drop to the excess pressure inside the bubble is

1 $\left(\frac{\mathrm{R}}{3 \mathrm{~d}}\right)^{\frac{1}{3}}$
2 $\left(\frac{\mathrm{R}}{8 \mathrm{~d}}\right)^{\frac{1}{3}}$
3 $\left(\frac{\mathrm{R}}{6 \mathrm{~d}}\right)^{\frac{1}{3}}$
4 $\left(\frac{\mathrm{R}}{24 \mathrm{~d}}\right)^{\frac{1}{3}}$
Mechanical Properties of Fluids

143103 In S.I. system, the total energy of the free surface of a liquid drop is $2 \pi$ times the surface tension of the liquid .The diameter of the drop is

1 $\sqrt{3} \mathrm{~m}$
2 $\sqrt{2} \mathrm{~m}$
3 $\sqrt{5} \mathrm{~m}$
4 $\sqrt{7} \mathrm{~m}$
Mechanical Properties of Fluids

143104 A $31.4 \mathrm{~kg}$ girl wearing high heel shoes balances her weight on a single heel. The diameter of the heel is $1 \mathrm{~cm}$. The pressure (in pascal) exerted by the heel on the floor is (Take $g=10 \mathrm{~m} / \mathrm{s}^{2}$ )

1 $2 \times 10^{6}$
2 $4 \times 10^{6}$
3 $6 \times 10^{6}$
4 $8 \times 10^{6}$
Mechanical Properties of Fluids

143105 A soap bubble of radius $r$ is blown further to increase its radius to $2 r$ under isothermal conditions. If $\sigma$ is the surface tension of the soap solution, the energy spent in doing so is

1 $4 \pi \sigma r^{2}$
2 $8 \pi \sigma r^{2}$
3 $12 \pi \sigma r^{2}$
4 $24 \pi \sigma r^{2}$