7. 8. The work done by a gas molecule in an isolated system is given by W=ae KT, where x is the displacement, k is the Boltzmann constant and T is the temperature. and are constants. Then the dimensions of will be: (a) [MLT-2] (b) [MLT-2] (c) [MLT2] In the given figure, a mass M is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is k. The mass oscillates on a frictionless surface with time period T and amplitude A. When the mass is in equilibrium position, as shown in the figure, another mass m is gently fixed upon it. New amplitude of oscillation will be: (d) [MLT] m M m M (a) A M-m 9. M (b) A M+m M-m (c) A M M+m (d) A M Four identical particles of equal masses 1kg made to move along the circumference of a circle of radius 1m under the actin of their own mutual gravitational attraction. The speed of each particle will be: (1+22)G (a) 2 (b)(1+22) (c)(22-1) (d) G(1+22) 10. A cube of side 'a' has point charges +Q located at each of its vertices except at the origin where the charge is -Q. The electric field at the centre of cube is: charge is +Q a +Q +Q +Q +Q Z 2Q a -2Q -Q (a) (x++2) (b) -(x++2) (c) (x++2) (d) 3/5 31/3 3/5 33a(++2) 11. Each side of a box made of metal sheet in cubic shape is 'a' at room temperature 'T', the coefficient of linear expansion of the metal sheet is 'a'. The metal sheet is heated uniformly, bya small temperature AT, so that its new temperature is T + AT. Calculate the increase in the volume of the metal box. (a) TaAT 3 (b) 3aAT (c) 4aAT (d) 4aAT