When a block of mass M is suspended by a long wire of length L, the length of the wire becomes (L + $$l$$). The elastic potential energy stored in the extended wire is :

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 :

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

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