The speed of air flows on the upper and lower surfaces of a wing of an aeroplane are v₁ and v₂ respectively. If A is the cross section area of the wing and ρ is the density of air, then the upward life is

• $\frac{1}{2}\mathrm{\rho } \mathrm{A}\left({\mathrm{v}}_2 - {\mathrm{v}}_1\right)$

• $\frac{1}{2}\mathrm{\rho } \mathrm{A}\left({\mathrm{v}}_1 + {\mathrm{v}}_2\right)$

• $\frac{1}{2} \mathrm{\rho } \mathrm{A} \left( {\mathrm{v}}_1^2 - {\mathrm{v}}_2^2 \right)$

• $\frac{1}{2}\mathrm{\rho } \mathrm{A} \left({\mathrm{v}}_1^2 + {\mathrm{v}}_2^2 \right)$

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