In this experiment, you will investigate the motion of a wooden strip. Set up the apparatus as shown in Fig. 1.1. The longer nail should be held in the boss and be placed through the top hole in the strip. The shorter nail should be placed through the bottom hole in the strip to support the slotted mass. The distance between the longer nail and the line on the strip is x, as shown in Fig. 1.1.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2018). The mark or mark type is shown in brackets.

1. [1] Value of x with unit in the range 23.5-24.5cm.
2. [1] Value of T with unit in the range 1.0–1.5s and to 0.1 s or better.
3. [5] Six sets of readings of x (different values) and time without help from the Supervisor and showing the correct trend scores 5 marks, five sets scores 4 marks etc.
4. [1] Range: Minimum value of x < 10.5 cm.
5. [1] Column headings: Each column heading must contain a quantity, a unit and a separating mark where appropriate. The presentation of the quantity and the unit must conform to accepted scientific convention e.g. T²x/s²m.
6. [1] Consistency: All raw values of x must be given to the nearest mm only.
7. [1] Significant figures: All values of x² must be given to the same number of significant figures as (or one more than) the number of significant figures in raw values of x.
8. [1] Calculation: Correct calculation of T²x.
9. [1] Axes: Sensible scales must be used, no awkward scales (e.g. 3:10 or fractions). Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Scales must be labelled with the quantity that is being plotted. Scale markings should be no more than three large squares apart.
10. [1] Plotting of points: All observations in the table must be plotted on the grid. Diameter of plotted points must be < half a small square (no "blobs”). Points must be plotted to an accuracy of half a small square.
11. [1] Quality: General trend of points on graph must be positive. All points in the table (at least 5) must be plotted on the grid. It must be possible to draw a straight line that is within ±0.005m² on the x-axis of all plotted points.
12. [1] Line of best fit: Judge by balance of all points on the grid about the candidate's line (at least 5 points). There must be an even distribution of points either side of the line along the full length. Allow one anomalous point only if clearly indicated by the candidate (i.e. circled or labelled). Line must not be kinked or thicker than half a small square.
13. [1] Gradient: The hypotenuse of the triangle used must be greater than half the length of the drawn line. The method of calculation must be correct. Do not allow Δx/Δy. Both read-offs must be accurate to half a small square in both the x and y directions. Sign of gradient on answer line must match graph.
14. [1] y-intercept: Correct read-off from a point on the line substituted into y = mx + c. Read-off must be accurate to half a small square in both x and y directions. or Intercept read directly from the graph with read-off at x = 0, accurate to half a small square.
15. [1] Value of A = candidate's gradient and value of B = candidate's intercept. The values must not be fractions.
16. [1] Unit for A correct (s²m⁻¹, s² cm⁻¹ or s²mm⁻¹) and unit for B correct (s²m, s² cm or s²mm).