The surface tension of a liquid is \(5\) N m^-1. If a film is held on a ring of area \(0.02\) ${\mathrm{m}}^2$, then its total surface energy is:
1. \(3\times\) ${10}^{-2}$ J
2. \(2\times\) ${10}^{-1}$ J
3. \(3\times\) ${10}^{-3}$J
4. ${10}^{-1}$ J

A liquid filled in a container has a plane meniscus. If $\mathrm{\theta }$ is the angle of contact, then:

The relative velocity of two adjacent layers of a liquid is \(6~\text{cm/s}\) and the perpendicular distance between layers is \(0.1~\text{mm}.\) The velocity gradient for liquid (in per second) is:
1. \(6\)
2. \(0.6\)
3. \(0.06\)
4. \(600\)

A large open tank with a square hole of side \(0.1\) cm in the wall at a depth of \(0.2\) m from the top is completely filled with a liquid. The rate of flow of liquid (in ${\mathrm{cm}}^3$/s) through the hole will be: 

The property of surface tension of the liquid is due to:

If two iron balls when fully immersed in water experience thrust force in the ratio of \(1:2\), then the ratio of the masses of the balls will be:
1. \(1:1\)
2. \(1:2\)
3. \(2:1\)
4. \(1:4\)

The reading of a spring balance when a block is suspended from it in the air is 60 N. This reading is changed to 40 N when the block is submerged in water. The specific gravity of the block, therefore, must be:
1. 3
2. 2
3. 6
4. 3/2

A beaker full of water is placed on a spring balance. If we put our finger in water without touching the beaker, how will the reading of the balance change?
[Take \(ρ _{finger}   >   ρ _{wate r}\)]