A small hole of area of cross-section 2 mm² present near the bottom of a fully filled open tank of height 2 m. Taking g = 10 m/s², the rate of flow of water through the open hole would be nearly :

Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by $$\Delta $$l on applying a force F, how much force is needed to stretch the second wire by the same amount?

The power radiated by a black body is P and it radiates maximum energy at wavelength, $$\lambda $$₀ . If the temperature of the black body is now changed so that it radiates maximum energy at wavelength $${3 \over 4}{\lambda _0}$$, the power radiated by it becomes nP. The value of n is

A small sphere of radius ‘r’ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to