This question was popular and fairly attempted by some candidates.  Some of the candidates who attempted it failed to record measured values to the required number of decimal places.  Measured values were reduced to 1 significant figure before plotting thereby making candidates lose marks.  For instance 0.0325 was reduced to 0.03.  This shifted the exact point away on the graph by two boxes.

The part (b) was not also properly answered by most candidates as some confused couple with moments.  Where definition of couple was successfully  stated, candidates could not give practical example/applications in everyday life as demanded by the question.

The demands of part (a) include the following:

1. evaluate five values of T and T²
2. Data should be measured to 1 decimal place and recorded in a composite table (showing h, t, T andT²);  (Trend; t increases as h increases)
3. The graph axes should be indicated and  reasonable scales selected to plot the five points required;
4. In order to determine the slope a large right angled triangle should be drawn on the graph line;
5. Precautions to ensure accurate results:

Ensured that the support of the bifilar pendulum is rigid.
Avoided parallax error in reading the metre rule/stop watch.
Ensured (smooth and regular) oscillations in a  horizontal plane.
Avoided zero error in the reading of stop watch/clock.
Repeated readings shown in table.

(b)(i)    Definition of the term Couple
- Two forces of equal magnitude acting in opposite directions but not along
 the same line.

1. Practical applications of a couple in everyday life:

-   Opening/closing of taps
-   Turning a steering wheel of a vehicle
-    Setting a fly wheel in motion about an axis through its centre
-    Motion of a spinning spindle
-    Riding/pedaling of bicycle
-    Turning a spanner