Question

Solution

Correct option is

W

Work done to below a bubble of radius r is In terms of volume, , we have Now, work done to blow a bubble of volume 8 V is  = 4 W.

SIMILAR QUESTIONS

Q1

A spherical small ball of density is gently released in a liquid of density . The initial acceleration of the free fall of the ball will be

Q2

A cylinder has a radius r. To what height h should it be filled with water so that the thrust on its walls is equal to that on its bottom?

Q3

The time period of a simple pendulum is T. The pendulum is oscillated with its bob immersed in a liquid of density . If the density of the bob is and viscous effect is neglected, the time period of the pendulum will be

Q4

A wooden block of mass m and density is tied to a string; the other end of the string is fixed to the bottom of a tank. The tank is filled with a liquid of density . What is the tension in the string.

Q5

A wooden ball of density is released from the bottom of a tank which is filled with a liquid of density up to a height h1. The ball rises in the liquid, emerges from its surface and attains a height h2 in air. If viscous effects are neglected, the ratio h2/h1 is

Q6

A glass plate (of negligible mass and thickness) is held against the end of a tube and pushed 10 cm under the surface of water. When released, the plate does not fall off. What depth of kerosene (relative density 0.8) must be poured into tube so that the plate just falls off?

Q7

Water rises to a height of 13.6 cm in a capillary tube dipped in water. When the same tube is dipped in mercury, it is depressed by cm. The angle of contact for water is zero and that for mercury 135o. The relative density of mercury is 13.6. The ratio of the surface tensions of mercury and water is

Q8

Two blocks A and B are made of different kinds of wood. Block A floats in water with of its above the surface water. Block B floats in water with of its volume below the surface of water. The ratio of the densities of A and B is

Q9

The pressures inside two soap bubbles are 1.002 and 1.004 atmospheres. Their respective volumes are in the ratio of

Q10

Water is flowing through a tube of radius r with a speed v. If this tube is joined to another tube of radius r/2, what is the speed of water in the second tube?