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

143082 Energy needed in breaking a liquid drop of radius $R$, into $n$ smaller drops each of radius $r$. is [T-Surface tension of the liquid]

1 $\left(4 \pi r^{2} n-4 \pi R^{2}\right) T$
2 $\left(\frac{4}{3} \pi r^{3} n-\frac{4}{3} \pi R^{3}\right) T$
3 $\left(4 \pi R^{2}-4 \pi r^{2}\right) n T$
4 $\left(4 \pi R^{2}-n 4 \pi r^{2}\right) / T$
Mechanical Properties of Fluids

143084 The excess pressure inside a spherical drop of radius $r$ of a liquid of surface tension $T$ is

1 directly proportional to $\mathrm{r}$ and inversely proportional to $T$
2 directly proportional to $\mathrm{T}$ and inversely proportional to $r$
3 directly proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
4 inversely proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
Mechanical Properties of Fluids

143085 A certain number of spherical drops of a liquid of radius $r$ coalesce to form a single big drop of radius $R$ and volume $V$. If $T$ is the surface tension of the liquid then

1 Energy $=4 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
2 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}+\frac{1}{\mathrm{R}}\right)$ is absorbed
3 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
4 Energy is neither released nor absorbed
Mechanical Properties of Fluids

143086 One end of a uniform glass capillary tube of radius $r=0.025 \mathrm{~cm}$ is immersed vertically in water to a depth $h=1 \mathrm{~cm}$. The excess pressure in $\mathrm{Nm}^{-2}$ required to blow an air bubble out of the tube
(Surface tension of water $=7 \times 10^{-2} \mathrm{Nm}^{-1}$ Density of water $=10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$
Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

1 $0.0048 \times 10^{5}$
2 $0.0066 \times 10^{5}$
3 $1.0048 \times 10^{5}$
4 $1.0066 \times 10^{5}$
Mechanical Properties of Fluids

143082 Energy needed in breaking a liquid drop of radius $R$, into $n$ smaller drops each of radius $r$. is [T-Surface tension of the liquid]

1 $\left(4 \pi r^{2} n-4 \pi R^{2}\right) T$
2 $\left(\frac{4}{3} \pi r^{3} n-\frac{4}{3} \pi R^{3}\right) T$
3 $\left(4 \pi R^{2}-4 \pi r^{2}\right) n T$
4 $\left(4 \pi R^{2}-n 4 \pi r^{2}\right) / T$
Mechanical Properties of Fluids

143084 The excess pressure inside a spherical drop of radius $r$ of a liquid of surface tension $T$ is

1 directly proportional to $\mathrm{r}$ and inversely proportional to $T$
2 directly proportional to $\mathrm{T}$ and inversely proportional to $r$
3 directly proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
4 inversely proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
Mechanical Properties of Fluids

143085 A certain number of spherical drops of a liquid of radius $r$ coalesce to form a single big drop of radius $R$ and volume $V$. If $T$ is the surface tension of the liquid then

1 Energy $=4 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
2 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}+\frac{1}{\mathrm{R}}\right)$ is absorbed
3 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
4 Energy is neither released nor absorbed
Mechanical Properties of Fluids

143086 One end of a uniform glass capillary tube of radius $r=0.025 \mathrm{~cm}$ is immersed vertically in water to a depth $h=1 \mathrm{~cm}$. The excess pressure in $\mathrm{Nm}^{-2}$ required to blow an air bubble out of the tube
(Surface tension of water $=7 \times 10^{-2} \mathrm{Nm}^{-1}$ Density of water $=10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$
Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

1 $0.0048 \times 10^{5}$
2 $0.0066 \times 10^{5}$
3 $1.0048 \times 10^{5}$
4 $1.0066 \times 10^{5}$
Mechanical Properties of Fluids

143082 Energy needed in breaking a liquid drop of radius $R$, into $n$ smaller drops each of radius $r$. is [T-Surface tension of the liquid]

1 $\left(4 \pi r^{2} n-4 \pi R^{2}\right) T$
2 $\left(\frac{4}{3} \pi r^{3} n-\frac{4}{3} \pi R^{3}\right) T$
3 $\left(4 \pi R^{2}-4 \pi r^{2}\right) n T$
4 $\left(4 \pi R^{2}-n 4 \pi r^{2}\right) / T$
Mechanical Properties of Fluids

143084 The excess pressure inside a spherical drop of radius $r$ of a liquid of surface tension $T$ is

1 directly proportional to $\mathrm{r}$ and inversely proportional to $T$
2 directly proportional to $\mathrm{T}$ and inversely proportional to $r$
3 directly proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
4 inversely proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
Mechanical Properties of Fluids

143085 A certain number of spherical drops of a liquid of radius $r$ coalesce to form a single big drop of radius $R$ and volume $V$. If $T$ is the surface tension of the liquid then

1 Energy $=4 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
2 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}+\frac{1}{\mathrm{R}}\right)$ is absorbed
3 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
4 Energy is neither released nor absorbed
Mechanical Properties of Fluids

143086 One end of a uniform glass capillary tube of radius $r=0.025 \mathrm{~cm}$ is immersed vertically in water to a depth $h=1 \mathrm{~cm}$. The excess pressure in $\mathrm{Nm}^{-2}$ required to blow an air bubble out of the tube
(Surface tension of water $=7 \times 10^{-2} \mathrm{Nm}^{-1}$ Density of water $=10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$
Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

1 $0.0048 \times 10^{5}$
2 $0.0066 \times 10^{5}$
3 $1.0048 \times 10^{5}$
4 $1.0066 \times 10^{5}$
Mechanical Properties of Fluids

143082 Energy needed in breaking a liquid drop of radius $R$, into $n$ smaller drops each of radius $r$. is [T-Surface tension of the liquid]

1 $\left(4 \pi r^{2} n-4 \pi R^{2}\right) T$
2 $\left(\frac{4}{3} \pi r^{3} n-\frac{4}{3} \pi R^{3}\right) T$
3 $\left(4 \pi R^{2}-4 \pi r^{2}\right) n T$
4 $\left(4 \pi R^{2}-n 4 \pi r^{2}\right) / T$
Mechanical Properties of Fluids

143084 The excess pressure inside a spherical drop of radius $r$ of a liquid of surface tension $T$ is

1 directly proportional to $\mathrm{r}$ and inversely proportional to $T$
2 directly proportional to $\mathrm{T}$ and inversely proportional to $r$
3 directly proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
4 inversely proportional to the product of $\mathrm{T}$ and $\mathrm{r}$
Mechanical Properties of Fluids

143085 A certain number of spherical drops of a liquid of radius $r$ coalesce to form a single big drop of radius $R$ and volume $V$. If $T$ is the surface tension of the liquid then

1 Energy $=4 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
2 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}+\frac{1}{\mathrm{R}}\right)$ is absorbed
3 Energy $=3 \mathrm{VT}\left(\frac{1}{\mathrm{r}}-\frac{1}{\mathrm{R}}\right)$ is released
4 Energy is neither released nor absorbed
Mechanical Properties of Fluids

143086 One end of a uniform glass capillary tube of radius $r=0.025 \mathrm{~cm}$ is immersed vertically in water to a depth $h=1 \mathrm{~cm}$. The excess pressure in $\mathrm{Nm}^{-2}$ required to blow an air bubble out of the tube
(Surface tension of water $=7 \times 10^{-2} \mathrm{Nm}^{-1}$ Density of water $=10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$
Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )

1 $0.0048 \times 10^{5}$
2 $0.0066 \times 10^{5}$
3 $1.0048 \times 10^{5}$
4 $1.0066 \times 10^{5}$