1. A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and the moment of inertial about it is I. A weight mg is attached to the cord at the end. The weight falls from rest. After falling through a distance 'h', the square of angular velocity of wheel will be: (a) 2mgh 1+mr (b) 2gh (c). 2gh 1+mr (d) 2mgh 1+2mr 2. The trajectory of a projectile in an vertical plane is y = ax - x, where a and are constants and x & y are respectively the horizontal and vertical distances of the projectile from the point of projection. The angle of projection 0 and the maximum height attained H are respectively given by: (a) tana, 4a (b) tana, a 4 (c) tan, (d) tan B 2 3. The length of metallic wire is when tension in it is T. It is l when the tension is T. The original length of the wire will be: (a) Tl+T T+T (b) Tl-Tl T- (c) Tl-T T-T (d) 2 4. A radioactive simple is undergoing a decay. At any time t, its activity is A and another time t, the What is the average life time for the sample? is A and activity is 5 (a) t-t In5 In(t+t) (b) 2 t-t In5 (c) (d) In5 t-t