(a) Diagram

(i)You are provided with two metre rules and other necessary apparatus.

(ii)Place one of the rules on a knife edge and determine its centre of gravity **C**. Mark this position with a piece of chalk.

(ii)Read and record the mass MR of the metre rule written on the reverse side of it.

(iv)Attach the mass **M** = 100 g firmly to the rule **AB** at **C** using sellotape.

(v)Suspend the metre rule by two parallel thread of length** h** = 40 cm each at the 10 cm and 90 cm marks. Ensure that the graduated face of the metre rule is facing upwards.

(vi)Set the rule **AB** into a small angular oscillation about the vertical axis through its centre of gravity.

(vii)Determine the time t for 20 complete oscillations. Evaluate the period **T** and **T**^{2}.

(viii)Read and record the value of **d** in metres.

(ix)Keeping **d** constant throughout the experiment, repeat the procedure for other values of **h** = 50, 60, 70 and 80 cm. In each case determine the corresponding values of** t**,** T** and **T**^{2}. Tabulate your readings.

(x)Plot a graph of** T**^{2}on the vertical axis and **h** on the horizontal axis.

(xi)Determine the slope **s**, of the graph.

Evaluate k = __s__

Q

where Q = __2__

25d^{2}

(xii)State **two** precautions taken to ensure accurate results

(b) (i) Define the term couple as it relates to rotational or oscillatory systems.

(ii) Give **two** practical applications of a couple in everyday life.