A-LevelPhysicsOscillations9702/33 · May/June 2019 · Q120 Marks

You may not need to use all of the materials provided. In this experiment, you will investigate the oscillations of a metre rule.

(a)• Set up the apparatus as shown in Fig. 1.1. • Attach the beaker to the block of wood using modelling clay. • The distance between the centre of each 150g mass and the nearest end of the rule is x. Adjust the apparatus so that the value of x is approximately 20cm and the rule is balanced on the beaker, as shown in Fig. 1.1. • Record x.[1]
(b)• Pull one end of the rule down through a short distance. • Release the end of the rule so that it oscillates. • Determine the period T of these oscillations.[2]
(c)Reduce x by changing the positions of the 150g masses on the rule. Measure and record x and T. Repeat until you have five sets of values. Record your results in a table.[7]
(d)(i)Plot a graph of T on the y-axis against x on the x-axis.[3]
(d)(ii)Draw the straight line of best fit.[1]
(d)(iii)Determine the gradient and y-intercept of this line.[2]
(e)It is suggested that the quantities T and x are related by the equation T = Px + Q where P and Q are constants. Using your answers in (d)(iii), determine the values of P and Q. Give appropriate units.[2]
(f)For one particular value of x, the value of T is the same as when there are no masses on the rule. • Remove the masses from the rule. • Balance the rule on the beaker and repeat (b). • Use your value of T and answers in (e) to calculate this value of x. Give your answer to three significant figures.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[1] Value of x in the range 18.0–22.0 cm with unit.
[1] Value of T in the range 2.50–4.50 s with unit.
[1] Evidence of at least two readings of nT where n ≥ 2.
[4] Five sets of readings of x and T (different values) showing the correct trend and without help from the Supervisor scores 4 marks, four sets scores 3 marks etc.
[1] Range: Xmin < 5.0 cm.
[1] Column headings: Each column heading must contain a quantity, a unit and a separating mark where appropriate. The presentation of the quantity and unit must conform to accepted scientific convention e.g. x/m.
[1] Consistency: All raw values of x must be given to the nearest mm only.
[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 correctly labelled with the quantity that is being plotted. Scale markings should be no more than three large squares apart.
[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.
[1] Quality: All observations in the table (at least 4) must be plotted on the grid. Trend of points on graph must be correct. It must be possible to draw a straight line that is within ±2.0 cm (to scale) of all the plotted points on the x-axis.
[1] Line of best fit: Judge by balance of all points on the grid about the candidate's line (at least 4 points). There must be an even distribution of points either side of the line along the full length. If there are 5 or more points, allow one anomalous point only if clearly indicated by the candidate. Lines must not be kinked or thicker than half a small square.
[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 ∆x/∆y. Both read-offs must be accurate to half a small square in both the x and y directions. Sign of gradient must match graph.
[1] y-intercept: Correct read-off from a point on the line and 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.
[1] Value of P = candidate's gradient and value of Q = candidate's intercept. The values must not be fractions.
[1] Units for P (s m⁻¹, s cm⁻¹ or s mm⁻¹) and Q (s) correct.
[1] Correct calculation of x [= (T – Q) / P] from values of T, P and Q and consistent sign.
[1] Final answer for x given to three significant figures.