A rectangular film of liquid is extended from (4 cm$\times$ $2$ $\mathrm{cm}$) to \((4 ~\text{cm}\times 5 ~\text{cm})\). If the work done is $3\times {10}^{-4}$ J, the value of the surface tension of the liquid is: 

1.	0.250 Nm-1	2.	0.125 Nm-1
3.	0.2 Nm-1	4.	8.0 Nm-1

 Two non-mixing liquids of densities $\rho$ and n$\rho$(n>1) are put in a container. The height of each liquid is h. A solid cylinder  floats with its axis vertical and length pL $\left(p<1\right)$ in the denser liquid. The density of the cylinder is d. The density d is equal to:

1. {2+(n+1)p}$\rho$             

2. {2+(n-1)p}$\rho$

3. {1+(n-1)p}$\rho$             

4. {1+(n+1)p}$\rho$

A wind with speed \(40~\text{m/s}\) blows parallel to the roof of a house. The area of the roof is \(250~\text{m}^2\). Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be: \(\left(\rho_{\text{air}}= 1.2~\text{kg/m}^3 \right)\)
1. \(4.8\times 10^{5}~\text{N}, ~\text{downwards}\)
2. \(4.8\times 10^{5}~\text{N}, ~\text{upwards}\)
3. \(2.4\times 10^{5}~\text{N}, ~\text{upwards}\)
4. \(2.4\times 10^{5}~\text{N}, ~\text{downwards}\)

Water rises to a height h in capillary tube . If the length of capillary tube above the surface of water is made less than h, then

(1) water rises upto the tip of capillary tube and then starts overflowing like a fountain

(2) water rises upto the top of capillary tube and stays there without overflowing

(3) water rises upto a point a little below the top and stays there

(4) water does not rise at all

Which two of the following five physical parameters have the same dimensions ?

(1) energy density 

(2) refractive index 

(3) dielectric constant 

(4) Young's modulus 

(5) magnetic field 

1. 2 and 4

2. 3 and 5 

3. 1 and 4 

4. 1 and 5

Two bodies are in equilibrium when suspended in water from the arms of a balance. The mass of one body is \(36\) g and its density is \(9\) g/cm³. If the mass of the other is \(48\) g, its density in g/cm³ will be:
1. $\frac{4}{3}$                                         

2. $\frac{3}{2}$

3. \(3\)                                           

4. \(5\)

An inverted bell lying at the bottom of a lake 47.6 m deep has 50 cm³ of air trapped in it. The bell is brought to the surface of the lake. The volume of the trapped air will be (atmospheric pressure = 70 cm of Hg and density of Hg = 13.6 g/cm³) 
(1) 350 cm³                               

(2) 300 cm³

(3) 250 cm³                               

(4) 22 cm³

A siphon in use is demonstrated in the following figure. The density of the liquid flowing in siphon is 1.5 gm/cc. The pressure difference between the point P and S will be

(1) ${10}^5 \mathrm{N}/\mathrm{m}$                                 

(2) $2\times {10}^5 \mathrm{N}/\mathrm{m}$

(3) Zero                                       

(4) Infinity 

The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. Ratio of density of mercury to that of air is ${10}^4$. The height of the hill is
(1) 250 m                             

(2) 2.5 km

(3) 1.25 km                           

(4) 750 m

A body of density ${\mathrm{d}}_1$ is counterpoised by Mg of weights of density ${\mathrm{d}}_2$ in air of density d. Then the true mass of the body is

(1) M                                   

(2) $\mathrm{M}\left(1-\frac{\mathrm{d}}{{\mathrm{d}}_2}\right)$

(3) $\mathrm{M}\left(1-\frac{\mathrm{d}}{{\mathrm{d}}_1}\right)$                       

(4) $\frac{\mathrm{M}(1-\mathrm{d}/{\mathrm{d}}_2)}{(1-\mathrm{d}/{\mathrm{d}}_1)}$