01. Surface Tension and Surface Energy
Mechanical Properties of Fluids

142791 The work done in increasing the size of a rectangular soap film with dimensions $8 \mathrm{~cm} \times$ $3.75 \mathrm{~cm}$ to $10 \mathrm{~cm} \times 6 \mathrm{~cm}$ is $2 \times 10^{-4} \mathrm{~J}$. The surface tension of the film in $\mathrm{N} \mathrm{m}^{-1}$ is

1 $3.3 \times 10^{-2}$
2 $1.65 \times 10^{-2}$
3 $8.25 \times 10^{-2}$
4 $6.6 \times 10^{-2}$
Mechanical Properties of Fluids

142793 Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

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

142794 The radius $R$ of the soap bubble is doubled under isothermal condition. If $T$ be the surface tension of soap bubble, the work done in doing so is given by

1 $32 \pi \mathrm{R}^{2} \mathrm{~T}$
2 $24 \pi R^{2} T$
3 $8 \pi R^{2} T$
4 $4 \pi R^{2} T$
Mechanical Properties of Fluids

142797 One drop of soap bubble of diameter $D$ breaks into 27 drops having surface tension $T$. The change in surface energy is

1 $2 \pi \mathrm{TD}^{2}$
2 $4 \pi \mathrm{TD}^{2}$
3 $\pi \mathrm{TD}^{2}$
4 $8 \pi \mathrm{TD}^{2}$
Mechanical Properties of Fluids

142798 The change in surface energy when a big spherical drop of radius $R$ is split into $n$ spherical droplets of radius $r$ is $(T=$ surface tension)

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

142791 The work done in increasing the size of a rectangular soap film with dimensions $8 \mathrm{~cm} \times$ $3.75 \mathrm{~cm}$ to $10 \mathrm{~cm} \times 6 \mathrm{~cm}$ is $2 \times 10^{-4} \mathrm{~J}$. The surface tension of the film in $\mathrm{N} \mathrm{m}^{-1}$ is

1 $3.3 \times 10^{-2}$
2 $1.65 \times 10^{-2}$
3 $8.25 \times 10^{-2}$
4 $6.6 \times 10^{-2}$
Mechanical Properties of Fluids

142793 Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

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

142794 The radius $R$ of the soap bubble is doubled under isothermal condition. If $T$ be the surface tension of soap bubble, the work done in doing so is given by

1 $32 \pi \mathrm{R}^{2} \mathrm{~T}$
2 $24 \pi R^{2} T$
3 $8 \pi R^{2} T$
4 $4 \pi R^{2} T$
Mechanical Properties of Fluids

142797 One drop of soap bubble of diameter $D$ breaks into 27 drops having surface tension $T$. The change in surface energy is

1 $2 \pi \mathrm{TD}^{2}$
2 $4 \pi \mathrm{TD}^{2}$
3 $\pi \mathrm{TD}^{2}$
4 $8 \pi \mathrm{TD}^{2}$
Mechanical Properties of Fluids

142798 The change in surface energy when a big spherical drop of radius $R$ is split into $n$ spherical droplets of radius $r$ is $(T=$ surface tension)

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

142791 The work done in increasing the size of a rectangular soap film with dimensions $8 \mathrm{~cm} \times$ $3.75 \mathrm{~cm}$ to $10 \mathrm{~cm} \times 6 \mathrm{~cm}$ is $2 \times 10^{-4} \mathrm{~J}$. The surface tension of the film in $\mathrm{N} \mathrm{m}^{-1}$ is

1 $3.3 \times 10^{-2}$
2 $1.65 \times 10^{-2}$
3 $8.25 \times 10^{-2}$
4 $6.6 \times 10^{-2}$
Mechanical Properties of Fluids

142793 Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

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

142794 The radius $R$ of the soap bubble is doubled under isothermal condition. If $T$ be the surface tension of soap bubble, the work done in doing so is given by

1 $32 \pi \mathrm{R}^{2} \mathrm{~T}$
2 $24 \pi R^{2} T$
3 $8 \pi R^{2} T$
4 $4 \pi R^{2} T$
Mechanical Properties of Fluids

142797 One drop of soap bubble of diameter $D$ breaks into 27 drops having surface tension $T$. The change in surface energy is

1 $2 \pi \mathrm{TD}^{2}$
2 $4 \pi \mathrm{TD}^{2}$
3 $\pi \mathrm{TD}^{2}$
4 $8 \pi \mathrm{TD}^{2}$
Mechanical Properties of Fluids

142798 The change in surface energy when a big spherical drop of radius $R$ is split into $n$ spherical droplets of radius $r$ is $(T=$ surface tension)

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

142791 The work done in increasing the size of a rectangular soap film with dimensions $8 \mathrm{~cm} \times$ $3.75 \mathrm{~cm}$ to $10 \mathrm{~cm} \times 6 \mathrm{~cm}$ is $2 \times 10^{-4} \mathrm{~J}$. The surface tension of the film in $\mathrm{N} \mathrm{m}^{-1}$ is

1 $3.3 \times 10^{-2}$
2 $1.65 \times 10^{-2}$
3 $8.25 \times 10^{-2}$
4 $6.6 \times 10^{-2}$
Mechanical Properties of Fluids

142793 Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

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

142794 The radius $R$ of the soap bubble is doubled under isothermal condition. If $T$ be the surface tension of soap bubble, the work done in doing so is given by

1 $32 \pi \mathrm{R}^{2} \mathrm{~T}$
2 $24 \pi R^{2} T$
3 $8 \pi R^{2} T$
4 $4 \pi R^{2} T$
Mechanical Properties of Fluids

142797 One drop of soap bubble of diameter $D$ breaks into 27 drops having surface tension $T$. The change in surface energy is

1 $2 \pi \mathrm{TD}^{2}$
2 $4 \pi \mathrm{TD}^{2}$
3 $\pi \mathrm{TD}^{2}$
4 $8 \pi \mathrm{TD}^{2}$
Mechanical Properties of Fluids

142798 The change in surface energy when a big spherical drop of radius $R$ is split into $n$ spherical droplets of radius $r$ is $(T=$ surface tension)

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

142791 The work done in increasing the size of a rectangular soap film with dimensions $8 \mathrm{~cm} \times$ $3.75 \mathrm{~cm}$ to $10 \mathrm{~cm} \times 6 \mathrm{~cm}$ is $2 \times 10^{-4} \mathrm{~J}$. The surface tension of the film in $\mathrm{N} \mathrm{m}^{-1}$ is

1 $3.3 \times 10^{-2}$
2 $1.65 \times 10^{-2}$
3 $8.25 \times 10^{-2}$
4 $6.6 \times 10^{-2}$
Mechanical Properties of Fluids

142793 Energy needed in breaking a drop of radius $R$ into $n$ drops of radii $r$ is given by

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

142794 The radius $R$ of the soap bubble is doubled under isothermal condition. If $T$ be the surface tension of soap bubble, the work done in doing so is given by

1 $32 \pi \mathrm{R}^{2} \mathrm{~T}$
2 $24 \pi R^{2} T$
3 $8 \pi R^{2} T$
4 $4 \pi R^{2} T$
Mechanical Properties of Fluids

142797 One drop of soap bubble of diameter $D$ breaks into 27 drops having surface tension $T$. The change in surface energy is

1 $2 \pi \mathrm{TD}^{2}$
2 $4 \pi \mathrm{TD}^{2}$
3 $\pi \mathrm{TD}^{2}$
4 $8 \pi \mathrm{TD}^{2}$
Mechanical Properties of Fluids

142798 The change in surface energy when a big spherical drop of radius $R$ is split into $n$ spherical droplets of radius $r$ is $(T=$ surface tension)

1 $4 \mathrm{R}^{2}\left(\mathrm{n}^{2 / 3}-1\right) \mathrm{T}$
2 $4 \mathrm{R}^{2} \pi\left(\mathrm{n}^{1 / 3}-1\right) \mathrm{T}$
3 $4 \pi \mathrm{R}^{2}\left(\mathrm{n}^{-1 / 3}-1\right) \mathrm{T}$
4 $4 \pi R^{2}\left(n^{-2 / 3}-1\right) T$