1
###
Work done in increasing the size of a soap bubble

Work done in increasing the size of a soap bubble from a radius of 3 cm to 5 cm is nearly. (Surface tension of soap solution = 0.03 Nm^{-1})

- 0.2π mJ
- 0.4π mJ
- 2π mJ
- 4π mJ

2
###
100 g of water is heated from 30°C to 50°C

100 g of water is heated from 30°C to 50°C ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is 4184 J/Kg/K)

- 2.1 kJ
- 4.2 kJ
- 8.4 kJ
- 84 kJ

3
###
The pressure that has to be applied to the ends of a steel wire

The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is: (For steel, Young’s modulus is 2×10^{11} N m^{–2} and coefficient of thermal expansion is 1.1×10^{-5} K^{-1})

- 2.2 × 10
^{6}Pa - 2.2 × 10
^{7}Pa - 2.2 × 10
^{8}Pa - 2.2 × 10
^{9}Pa

4
###
Water is flowing continuously from a tap having an internal diameter

Water is flowing continuously from a tap having an internal diameter 8×10^{-3} m. The water velocity as it leaves the tap is 0.4 ms^{-1}. The diameter of the water stream at a distance 2×10^{-1} m below the tap is close to

- 7.5 × 10
^{-3}m - 9.6 × 10
^{-3}m - 3.6 × 10
^{-3}m - 5.0 × 10
^{-3}m

5
###
If mass-energy equivalence is taken into account

If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should

- first increase then decrease
- increase
- decrease
- remain unchanged

6
###
A cylinder of height 20 m is completely filled with water. The velocity of efflux of water

A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in ms^{-1}) through a small hole on the side wall of the cylinder near its bottom is

- 20
- 25.5
- 10
- 5

7
###
The flow rate of water from a tap of diameter 1.25 cm is 0.48 L/min

The flow rate of water from a tap of diameter 1.25 cm is 0.48 L/min. The coefficient of viscosity of water is 10^{-3} Pa s. After sometime the flow rate is increased to 3 L/min. Characterize the flow for both the flow rates.

8
###
If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter

If it takes 5 minutes to fill a 15 litre bucket from a water tap of diameter 2/√π cm then the Reynolds number for the flow is (density of water = 10^{3} kg/m^{3} and viscosity of water = 10^{-3} Pa.s) close to:

- 5500
- 11,000
- 550
- 1100