- A billiard ball A moving with an initial speed of 1 m/s, undergoes a perfectly elastic collision with another identical ball B at rest. A is scattered through an angle of 30˚. What is the angle of recoil of B? What is the speed of ball A after the collision?

- Two springs have force constants K
_{1}and K_{2}(K_{1}> K_{2}).On which spring is more work will be done if : (i) when they are stretched by the same force? and (ii) they are stretched through the same distance?

**Show that the acceleration of free fall g at the surface of earth and the gravitational constant G are related by the expression**

g = 4\3 Π p G R,

- The radius of curvature of a concave mirror ,measured by a spherometer ,is given by

R = l^{2} /6h + h/2 The value of l and h are 4.0 cm and 0.065 cm respectively, where l measured by a meter scale and h by a spherometer.Find the error in the measurement of R.