Physics 9702/34 May/June 2023: question paper and mark scheme

Mark scheme

1(a) Value of M with unit and in range 10–100 g. 1 Value of T with unit and in range 0.950–2.00 s. 1 Repeats: At least two measurements of at least 5T. 1 1(b) Six sets of readings of M (different values, may include 0 g) and T (or time) with correct trend (as M increases T increases) 4 and without help from the Supervisor scores 4 marks, five sets scores 3 marks etc. Range: Mmin ⩽10 g and Mmax ⩾ 70 g. 1 Column headings: 1 Each column heading must contain a quantity and a unit where appropriate. The presentation of quantity and unit conforms to accepted scientific convention e.g. M 2 / g2. Consistency: 1 All values of raw time must be given to the nearest 0.01s or all to the nearest 0.1 s. Significant figures: 1 Values of T2 must be given to the same number of s.f. as (or one more than) the number of s.f. in the corresponding T. Calculation: Values of T2 calculated correctly. 1 1(c)(i) Axes: 1 Axes must be labelled with the correct quantities. Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Scale markings are no more than 2 cm apart (one large square). Sensible scales must be used. Scale must not be awkward (e.g. 3:10 or fractions). Plotting of points: 1 All observations in the table must be plotted on the grid. Diameter of plotted points must be less than half a small square. Points must be plotted to an accuracy of half a small square in both x and y directions. Quality: 1 Trend of points must be positive. All points in the table must be plotted on the grid. It must be possible to draw a straight line that is within ± 500 g2 (to scale) on the M 2 axis of all plotted points. 1(c)(ii) Line of best fit: 1 ‘Best fit’ is judged by balance of all points on the grid (at least 5 points) about the candidate’s line. There must be an even distribution of points either side of the line along the full length. Lines must not be kinked or thicker than half a small square. Some candidates may choose to identify an anomalous point. If they identify one point as anomalous (e.g. by circling or labelling) then this point is to be disregarded when judging the line of best fit. There must be at least 5 points left after the anomalous point is disregarded. 1(c)(iii) Gradient: 1 The hypotenuse of the triangle used should be greater than half the length of the drawn line. Both read-offs must be accurate to half a small square in both x and y directions. The method of calculation must be correct, not Δx / Δy. The gradient sign on the answer line must be consistent with the graph drawn. y-intercept: 1 Intercept read directly from the graph, with read-off at M2 = 0, accurate to half a small square in y direction. or Correct read-off from a point on the line and substituted correctly into y = mx + c or an equivalent expression. Read-off is accurate to half a small square in both x and y directions. 1(d) Value of a = candidate’s gradient and value of b = candidate’s intercept. 1 Values must not be written as fractions or given to only one significant figure. Correct units for a and b (e.g. s2 g–2 for a and s2 for b). 1

Mark scheme

2(a) Value for L with unit, to nearest mm and in range 11.7–12.7 cm. 1 Value for T0 with unit and to nearest degree. 1 2(b)(i) Value for x1 with unit and to nearest mm. 1 2(b)(ii) Value for T greater than T0. 1 Value of x2 different from x1. 1 2(b)(iii) Correct calculation of (x1 – x2). 1 2(b)(iv) Percentage uncertainty in (x1 – x2) based on absolute uncertainty in the range 0.2–0.5 cm. 1 Correct method of calculation to obtain percentage uncertainty e.g. (absolute uncertainty / value from (b)(iii)) × 100. If several readings have been taken, then the absolute uncertainty can be half the range (but not zero) provided the working is shown clearly. 2(c) Second values of L, x1, T and x2. 1 Second L less than first L. 1 2(d)(i) Two values of k calculated correctly. 1 The final k values must not be written as fractions. 2(d)(ii) Justification for significant figures in k linked to significant figures in (x1 – x2), L and (T – T0). 1 2(e) Calculation of percentage difference between candidate’s two k values. 1 Comparison of percentage difference with 20% leading to a consistent conclusion. 2(f)(i) A Two readings are not enough to draw a (valid) conclusion (not “not enough for accurate results”, “few readings”). 4 B Difficult to measure x or height with a reason e.g. rod moves/rule not vertical/ruler moves. C (x1 – x2) is small so large uncertainty or large % uncertainty in (x1 – x2). D Difficult to measure T or water temperature with a reason e.g. T varies with position in measuring cylinder/thermometer touches sides of cylinder/cannot measure x and T at the same time/T decreases rapidly. E T0 or room temperature may change during the experiment. F Difficulty with pipe e.g. difficult to measure L because pipe is curved/pipe does not expand as expected/L is not the distance between the holes. G Difficulty with string e.g. string changes length when wet. 1 mark for each point up to a maximum of 4. 2(f)(ii) A Take more readings (for different values of x) and plot a graph or take more readings and compare k values (not 4 “repeat readings” on its own). B Clamp rule/use a plumb line. C Increase length of rod/pipe. D Use a stirrer for the water/clamp thermometer/thermostatically controlled water bath. E Measure T0 just before water is added. F Use tape measure/string and ruler or make L the distance between the holes. G Use named waterproof material e.g. nylon string/plastic/metal wire. 1 mark for each point up to a maximum of 4.