A body of mass 2 kg makes an eleastic collision with a second body at rest and continues to move in the original direction but with one fourth of its original speed. What is the mass of the second body ?

A simple pendulum oscillating in air has period T. The bob of the pendulum is completely immersed in a non-viscous liquid. The density of the liquid is 1/16 th of the material of the bob. If the bob is inside liquid all the time, its period of oscillation in this liquid is :

Following figure shows two processes A and B for a gas. If $$\Delta $$Q_A and $$\Delta $$Q_B are the amount of heat absorbed by the system in two cases, and $$\Delta $$U_A and $$\Delta $$U_B are changes in internal energies, respectively, then :

A wire of resistance R is bent to form a square ABCD as shown in the figure. The effective resistance between E and C is : (E is mid-point of arm CD)