You are provided with a uniform metre rule, a knife edge, some masses and other necessary apparatus.

(i) Determine and record the centre of gravity of the metre rule.

(ii) Fix the 100 g mass marked N at a point Y, the 80 cm mark of the rule using an adhesive.

(iii) Suspend another 100 g mass marked M at X, a distance A = 10 cm from the 0 cm mark of the rule.

(iv) Balance the arrangement horizontally on the knife edge as shown in the diagram above.

(v) Measure and record the distance B of the knife edge from the 0 cm mark of the rule.

(vi) Repeat the procedure for** four** other values of **A** = 15, 20, 25, and 30 cm.

(vii) Measure and record the corresponding values of **B** in each case. Tabulate your readings.

(viii) Plot a graph of **B** on the vertical axis against **A** on the horizontal axis.

(ix) Determine the slope, s, of the graph. Also determine the intercept, c, on the vertical axis.

(x) Evaluate (A) ** ** = k1 = __1 – 2s__ 100;

** **s** **

** **(B) ** ** = k2 = __2c__ 160.

** ** s** **

** **(xi) State **two** precautions taken to obtain accurate results. [21 marks]

(b) (i) Define *moment of a force about a point*. [2 marks]

(ii) State two conditions under which a rigid body at rest remains in equilibrium when acted upon by three non-parallel coplanar forces [2 marks]