Surface Tension
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361301 A metal wire of density \(\rho\) floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is proportional to ( where \(T = \) surface tension of water, \(g = \) gravitational acceleration)

1 \(\sqrt {\frac{T}{{\pi \rho g}}} \)
2 \(\sqrt {\frac{{\pi \rho g}}{T}} \)
3 \(\frac{T}{{\pi \rho g}}\)
4 \(\frac{{\pi \rho g}}{T}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361302 A pin or a needle floats on the surface of water, the reason for this is

1 Surface tension
2 Less weight
3 Upthrust of liquid
4 None of the above
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361303 Bubbles are made by dipping a circular ring of radius \(b\) in a soap solution and then blowing air on the film formed on the ring. Assume that the blown air is in the form of a cylinder of radius \(b\). It has speed \(v\) and stops after striking the surface of the bubble being formed. The bubble grows spherically. Let the radius \(R\) of the bubble \((>>b)\), so that the air strikes the bubbles surface perpendicularly. The surface tension of the solution is \(T\) and air density is \(\rho\). The radius of the bubble when it separates from the ring is (neglect the mass of the bubble).
supporting img

1 \(\dfrac{4 T}{\rho V^{2}}\)
2 \(\dfrac{T}{\rho V^{2}}\)
3 \(\dfrac{T}{4 \rho V^{2}}\)
4 \(\frac{{2T}}{{\rho {V^2}}}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361304 A thin metal ring of internal radius \(8\;cm\) and external radius \(9\;cm\) is supported horizontally from the pan of a balance so that it comes in contact with water in a glass vessel. It is found that an extra weight of \(7.48\;g\) is required to pull the ring out of water. The surface tension of water is

1 \(80 \times {10^{ - 3}}\;N/m\)
2 \(75 \times {10^{ - 3}}\;N/m\)
3 \(65 \times {10^{ - 3}}\;N/m\)
4 \(70 \times {10^{ - 3}}\;N/m\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361305 What is the force required to take away a flat plate of radius \(10\;cm\) from the surface of water, if surface tension of water is \(72 \times {10^{ - 3}}N{m^{ - 1}}?\)

1 \(5 \times {10^{ - 2}}\;N\)
2 \(4.5 \times {10^{ - 2}}\;N\)
3 \(3 \times {10^{ - 2}}\;N\)
4 \(3 \times {10^3}\;N\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361301 A metal wire of density \(\rho\) floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is proportional to ( where \(T = \) surface tension of water, \(g = \) gravitational acceleration)

1 \(\sqrt {\frac{T}{{\pi \rho g}}} \)
2 \(\sqrt {\frac{{\pi \rho g}}{T}} \)
3 \(\frac{T}{{\pi \rho g}}\)
4 \(\frac{{\pi \rho g}}{T}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361302 A pin or a needle floats on the surface of water, the reason for this is

1 Surface tension
2 Less weight
3 Upthrust of liquid
4 None of the above
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361303 Bubbles are made by dipping a circular ring of radius \(b\) in a soap solution and then blowing air on the film formed on the ring. Assume that the blown air is in the form of a cylinder of radius \(b\). It has speed \(v\) and stops after striking the surface of the bubble being formed. The bubble grows spherically. Let the radius \(R\) of the bubble \((>>b)\), so that the air strikes the bubbles surface perpendicularly. The surface tension of the solution is \(T\) and air density is \(\rho\). The radius of the bubble when it separates from the ring is (neglect the mass of the bubble).
supporting img

1 \(\dfrac{4 T}{\rho V^{2}}\)
2 \(\dfrac{T}{\rho V^{2}}\)
3 \(\dfrac{T}{4 \rho V^{2}}\)
4 \(\frac{{2T}}{{\rho {V^2}}}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361304 A thin metal ring of internal radius \(8\;cm\) and external radius \(9\;cm\) is supported horizontally from the pan of a balance so that it comes in contact with water in a glass vessel. It is found that an extra weight of \(7.48\;g\) is required to pull the ring out of water. The surface tension of water is

1 \(80 \times {10^{ - 3}}\;N/m\)
2 \(75 \times {10^{ - 3}}\;N/m\)
3 \(65 \times {10^{ - 3}}\;N/m\)
4 \(70 \times {10^{ - 3}}\;N/m\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361305 What is the force required to take away a flat plate of radius \(10\;cm\) from the surface of water, if surface tension of water is \(72 \times {10^{ - 3}}N{m^{ - 1}}?\)

1 \(5 \times {10^{ - 2}}\;N\)
2 \(4.5 \times {10^{ - 2}}\;N\)
3 \(3 \times {10^{ - 2}}\;N\)
4 \(3 \times {10^3}\;N\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361301 A metal wire of density \(\rho\) floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is proportional to ( where \(T = \) surface tension of water, \(g = \) gravitational acceleration)

1 \(\sqrt {\frac{T}{{\pi \rho g}}} \)
2 \(\sqrt {\frac{{\pi \rho g}}{T}} \)
3 \(\frac{T}{{\pi \rho g}}\)
4 \(\frac{{\pi \rho g}}{T}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361302 A pin or a needle floats on the surface of water, the reason for this is

1 Surface tension
2 Less weight
3 Upthrust of liquid
4 None of the above
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361303 Bubbles are made by dipping a circular ring of radius \(b\) in a soap solution and then blowing air on the film formed on the ring. Assume that the blown air is in the form of a cylinder of radius \(b\). It has speed \(v\) and stops after striking the surface of the bubble being formed. The bubble grows spherically. Let the radius \(R\) of the bubble \((>>b)\), so that the air strikes the bubbles surface perpendicularly. The surface tension of the solution is \(T\) and air density is \(\rho\). The radius of the bubble when it separates from the ring is (neglect the mass of the bubble).
supporting img

1 \(\dfrac{4 T}{\rho V^{2}}\)
2 \(\dfrac{T}{\rho V^{2}}\)
3 \(\dfrac{T}{4 \rho V^{2}}\)
4 \(\frac{{2T}}{{\rho {V^2}}}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361304 A thin metal ring of internal radius \(8\;cm\) and external radius \(9\;cm\) is supported horizontally from the pan of a balance so that it comes in contact with water in a glass vessel. It is found that an extra weight of \(7.48\;g\) is required to pull the ring out of water. The surface tension of water is

1 \(80 \times {10^{ - 3}}\;N/m\)
2 \(75 \times {10^{ - 3}}\;N/m\)
3 \(65 \times {10^{ - 3}}\;N/m\)
4 \(70 \times {10^{ - 3}}\;N/m\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361305 What is the force required to take away a flat plate of radius \(10\;cm\) from the surface of water, if surface tension of water is \(72 \times {10^{ - 3}}N{m^{ - 1}}?\)

1 \(5 \times {10^{ - 2}}\;N\)
2 \(4.5 \times {10^{ - 2}}\;N\)
3 \(3 \times {10^{ - 2}}\;N\)
4 \(3 \times {10^3}\;N\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361301 A metal wire of density \(\rho\) floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is proportional to ( where \(T = \) surface tension of water, \(g = \) gravitational acceleration)

1 \(\sqrt {\frac{T}{{\pi \rho g}}} \)
2 \(\sqrt {\frac{{\pi \rho g}}{T}} \)
3 \(\frac{T}{{\pi \rho g}}\)
4 \(\frac{{\pi \rho g}}{T}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361302 A pin or a needle floats on the surface of water, the reason for this is

1 Surface tension
2 Less weight
3 Upthrust of liquid
4 None of the above
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361303 Bubbles are made by dipping a circular ring of radius \(b\) in a soap solution and then blowing air on the film formed on the ring. Assume that the blown air is in the form of a cylinder of radius \(b\). It has speed \(v\) and stops after striking the surface of the bubble being formed. The bubble grows spherically. Let the radius \(R\) of the bubble \((>>b)\), so that the air strikes the bubbles surface perpendicularly. The surface tension of the solution is \(T\) and air density is \(\rho\). The radius of the bubble when it separates from the ring is (neglect the mass of the bubble).
supporting img

1 \(\dfrac{4 T}{\rho V^{2}}\)
2 \(\dfrac{T}{\rho V^{2}}\)
3 \(\dfrac{T}{4 \rho V^{2}}\)
4 \(\frac{{2T}}{{\rho {V^2}}}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361304 A thin metal ring of internal radius \(8\;cm\) and external radius \(9\;cm\) is supported horizontally from the pan of a balance so that it comes in contact with water in a glass vessel. It is found that an extra weight of \(7.48\;g\) is required to pull the ring out of water. The surface tension of water is

1 \(80 \times {10^{ - 3}}\;N/m\)
2 \(75 \times {10^{ - 3}}\;N/m\)
3 \(65 \times {10^{ - 3}}\;N/m\)
4 \(70 \times {10^{ - 3}}\;N/m\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361305 What is the force required to take away a flat plate of radius \(10\;cm\) from the surface of water, if surface tension of water is \(72 \times {10^{ - 3}}N{m^{ - 1}}?\)

1 \(5 \times {10^{ - 2}}\;N\)
2 \(4.5 \times {10^{ - 2}}\;N\)
3 \(3 \times {10^{ - 2}}\;N\)
4 \(3 \times {10^3}\;N\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361301 A metal wire of density \(\rho\) floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is proportional to ( where \(T = \) surface tension of water, \(g = \) gravitational acceleration)

1 \(\sqrt {\frac{T}{{\pi \rho g}}} \)
2 \(\sqrt {\frac{{\pi \rho g}}{T}} \)
3 \(\frac{T}{{\pi \rho g}}\)
4 \(\frac{{\pi \rho g}}{T}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361302 A pin or a needle floats on the surface of water, the reason for this is

1 Surface tension
2 Less weight
3 Upthrust of liquid
4 None of the above
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361303 Bubbles are made by dipping a circular ring of radius \(b\) in a soap solution and then blowing air on the film formed on the ring. Assume that the blown air is in the form of a cylinder of radius \(b\). It has speed \(v\) and stops after striking the surface of the bubble being formed. The bubble grows spherically. Let the radius \(R\) of the bubble \((>>b)\), so that the air strikes the bubbles surface perpendicularly. The surface tension of the solution is \(T\) and air density is \(\rho\). The radius of the bubble when it separates from the ring is (neglect the mass of the bubble).
supporting img

1 \(\dfrac{4 T}{\rho V^{2}}\)
2 \(\dfrac{T}{\rho V^{2}}\)
3 \(\dfrac{T}{4 \rho V^{2}}\)
4 \(\frac{{2T}}{{\rho {V^2}}}\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361304 A thin metal ring of internal radius \(8\;cm\) and external radius \(9\;cm\) is supported horizontally from the pan of a balance so that it comes in contact with water in a glass vessel. It is found that an extra weight of \(7.48\;g\) is required to pull the ring out of water. The surface tension of water is

1 \(80 \times {10^{ - 3}}\;N/m\)
2 \(75 \times {10^{ - 3}}\;N/m\)
3 \(65 \times {10^{ - 3}}\;N/m\)
4 \(70 \times {10^{ - 3}}\;N/m\)
PHXI10:MECHANICAL PROPERTIES OF FLUIDS

361305 What is the force required to take away a flat plate of radius \(10\;cm\) from the surface of water, if surface tension of water is \(72 \times {10^{ - 3}}N{m^{ - 1}}?\)

1 \(5 \times {10^{ - 2}}\;N\)
2 \(4.5 \times {10^{ - 2}}\;N\)
3 \(3 \times {10^{ - 2}}\;N\)
4 \(3 \times {10^3}\;N\)