Q: Two metal rods of the same length and are of cross – section are fixed end to end between rigid supports. The materials of the rods have Young’s moduli Y1 and Y2 , and coefficients of linear expansion α1 and α2. The junction between the rods does not shift, if the rods are cooled, when
(a) Y1 α1 = Y2 α2
(b) Y12 α1 =Y22 α2
(c) Y1 α2 = Y2 α1
(d) Y1 α12 = Y2 α22
Sol: As the junction between the rods does not shift, tension in both the rods must be the same.
Q: 1 cm3 of water at its boiling point absorbs 540 calories of heat to become steam with a volume of 1671 cm3. If the atmospheric pressure = 1.013 ×105 N/m2 and the mechanical equivalent of heat = 4.19 J/cal., the energy spent in this process in overcoming intermolecular forces is
Q: A cylinder fitted with a piston contains 0.2 mole of air at temperature 27 °C. The piston is pushed so slowly that the air within the cylinder remains in thermal equilibrium with the surrounding s. Find the approximate work done by the system if the final volume is twice initial volume.