a) Given a retort stand and clamp, a stout pin, a simple pendulum and a pencil, describe how you would use these apparatus to determine the centre of gravity of an irregularly shaped piece of cardboard of a moderate size.

(b) Using a suitable diagram, explain how the following can be obtained from a velocity-time graph:

(i)  acceleration;
(ii) total distance covered.                                                                                   

(c ) A body at rest is given an initial uniform acceleration of 6.0 ms\(^{-2}\) for 20s after which the acceleration is reduced to 4.0 ms\(^{-2}\) for the next 10s.
The body maintains the speed attained for 30s.
           
Draw the velocity-time graph of the motion using the information given above.  From the graph, calculate the:

• maximum speed attained during the motion;
• total distance traveled during the first 30 s;
• average speed during the same time interval as in (ii) above.