A thick rope of rubber of density 1.5×103kg/m3 and Young's modulus 5×106N/m2 , 8m length is hung from the ceiling of a room , the increases in its length due to its own weight is :
(g=10m/s2)
A 5 metre long wire is fixed to the ceiling. A weight of 10 kg is hung at the lower end and is 1 metre above the floor. The wire was elongated by 1 mm. The energy stored in the wire due to stretching is