A small spherical drop fall from rest in viscous liquid. Due to friction, heat is produced. The correct relation between the rate of production of heat and the radius of the spherical drop at terminal velocity will be

• $\frac{\mathrm{dH}}{\mathrm{dt}} \propto \frac{1}{{\mathrm{r}}^5}$

• $\frac{\mathrm{dH}}{\mathrm{dt}} \propto {\mathrm{r}}^4$

• $\frac{\mathrm{dH}}{\mathrm{dt}} \propto \frac{1}{{\mathrm{r}}^4}$

• $\frac{\mathrm{dH}}{\mathrm{dt}} \propto {\mathrm{r}}^5$

A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be

Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is

If two soap bubbles of different radii are connected by a tube,

A steam of a liquid of density ρ flowing horizontally with speed v rushes out of a tube of radius r and hits a vertical wall nearly normally. Assuming that the liquid does not rebound from the wall, the force exerted on the wall by the impact of the liquid is given by

A wide hose pipe is held horizontally by a fireman. It delivers water through a nozzle at one litre per second. On increasing the pressure. this increases to two litres per second. The firman has now to

A liquid is allowed into a tube of truncated cone shape. Identify the correct statement from the following.

Mercury boils at 367° C. However, mercury thermometers are made such that they can measure temperature upto 500°C. This is done by

Aerofils are so designed that the speed of air