EJC 2023 J2 H2 PRELIM P4 MS

©EJC 2023 9749/04/J2H2Prelim/2023 [Turn over EUNOIA JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS 2023 9749 PHYSICS MARK SCHEME Paper 4 – Practical Qns Answer Marks 1aiii • Maximum reading for w is 6.5 cm • Correct precision of 0.1 cm and corresponding unit • Repeated readings 1 1bii • No. of oscillations stated clearly • Measured time precise to 0.01 s with correct unit Duration > 10s • Repeated readings 1 • Period calculated to least s.f. with correct units 1 1ci Largest value is 6.3 cm (Accept 6.0-6.5 cm) Corresponds to the width of the bull dog clip provided OR Largest value is 8 cm (Accept 7-14 cm) Oscillation dies down too quickly when w is larger. 1 1cii • All headings accurately labelled with correct units. • Repeated readings for t • At least 6 sets of data collected 1 • w / cm recorded to 0.1 cm • t / s recorded 0.01 s • t > 10s • N, n recorded 1 • t average calculated and given to 0.01 s (same d.p. as t) • T calculated and given to least s.f. • 1/w calculated and given to least s.f. 1 If table is split (e.g. 1/w or T in a separate table, minus 1 mark from 1cii MINUS 1 1di • Axes labelled with correct quantity and corresponding units • Labelled at every 2 cm or 4 cm interval • Plotted points cover at least half of the grid given 1 • All points from table are plotted correctly (should not have more crosses than data sets from the table) • Best fit straight line drawn with anomalous points clearly labelled as “anomalous”, where applicable (not allowed to consider points as anomalous if data set is less than 6 sets) 1

2 ©EJC 2023 9749/04/J2H2Prelim/2023 Qns Answer Marks 1dii • One point clearly identified – this point cannot be an anomalous point. • Expected T read to half the precision of a grid • Measured T can be read to the precision of the grid OR can be read from the table directly. • Difference in T calculated with correct units 1 1diii If candidate drew a straight line: If the relationship is valid, the plot of T against 1/w should give a line through the origin. OR The relationship is not valid because the best fit (straight) line does not pass through the origin. OR, if candidate drew a curve: If the equation is valid, the plot of T against 1/w should give a straight line through the origin. 1 The y-intercept of the graph is 0.6, and the difference of the y-intercept to zero is larger than the maximum difference between the best fit line and the data points as calculated in (d)(i), which is 0.3. Hence, the graph is a straight line which does not pass through the origin, and therefore, the results do not support the relationship. OR, if candidate drew a straight line: From the plot in (d)(i), the best fit line fit a curve, not a straight line. The difference in (d)(ii) shows a maximum percentage difference of ____ for the value of T based on a best fit straight line, which is larger than 10%. Hence, my results do not support the relationship. OR, if candidate drew a curved line: The difference in (d)(ii) shows a maximum percentage difference of ____ for the value of T, which is smaller than 10% (min 10%, max 20%). Hence, my results support a curved line and do not support the given relationship. 1 1ei • All headings accurately labelled with correct units. • Repeated readings for t • 4 sets of data collected 1 • c / mm recorded to 0.01 mm, around 0.10 mm, 0.20 mm, 0.23 mm and 0.30 mm (cannot exceed 0.50 mm) • t / s recorded 0.01 s • t > 10 s • N, n recorded 1 • t average calculated to 0.01 s • T calculated and given to least s.f. 1 If data is not presented in a single table, minus 1 mark from 1ei MINUS 1 1eii • Axes labelled with correct quantity and units 1

3 ©EJC 2023 9749/04/J2H2Prelim/2023 [Turn over Qns Answer Marks • Labelled at every 2 cm or 4 cm interval • Plotted points cover at least half of the grid given • All points in table are plotted correctly • Cannot have anomaly (too little data points) • Best fit line drawn (can accept straight line too) • Trend is correct: negative gradient 1 1eiii As c increases, T decreases at a decreasing/increasing/constant rate. (Conclusion should be based on candidate’s results.) Do not accept “inverse” or “opposite” relationship. 1 1f Measure independent and dependent variables using appropriate measuring instruments. • Measure the length 𝑙 of the rod with a metre rule / measuring tape • Measure the time taken for oscillations using a stopwatch • Repeat steps to collect a set of readings by varying 𝑙 1 Statement of what graph to plot; Expected observation if the relationship is valid. • Plot a graph of T against 𝑙2 • If T is directly proportional 𝑙2, a straight line graph through the origin will be obtained. 1 Any one of the control of variables correctly identified. • The axis of rotation should pass through the geometric centre of the rod, by aligning the centre of the rod to the centre of the strip of paper • Use the same (thickness/width/length of) paper strip for the oscillating system. • Use the same diameter/mass/volume/density for the rod Do not accept “same material of the rod”, since the material (wood) has already been given. 1 2ai • E recorded to correct precision of 1 mV or 0.001 V • Repeated readings for E • Value should be 1.3 V – 1.9 V 1 2aiii • L recorded to correct precision of 0.001 m or 0.1 cm • Value should be 40 cm – 48 cm • Repeated readings for L 1 2bii 2biv • I recorded to correct precision of 0.0001 A or 0.1 mA • x recorded to correct precision of 0.001 m or 0.1 cm • Repeated readings x and I 1 2c • All headings accurately labelled with correct units. • Repeated readings for I 1 • x / cm recorded to 0.1 cm • I / mA recorded 0.1 mA 1

4 ©EJC 2023 9749/04/J2H2Prelim/2023 Qns Answer Marks • As x increases, I increases. • At least 6 sets of data collected • Range of x is at least 20 cm 1 • <I> calculated and given to 1 d.p. (same as I) • 1 〈𝐼〉 calculated and given to least s.f. (3 s.f.) 1 2d Linearising equation and statement. • Plotting 1 I against x should give a straight-line graph with gradient -P and y-intercept Q. 1 Axes: • Sensible scales must be used, no awkward scales (only allow 1, 2, 5). • 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 and units which are being plotted. • Scale markings should be no more than 4 cm apart. • Must label origin if a plot falls within the first 2 cm. 1 Plotting of points: • All observations must be plotted on the grid. • Plots must be accurate to within half a small square in both x and y directions. 1 Line of best-fit • Judged by balance of all points on the grid about the line. There must be an even distribution of points either side of the line along the full length. • One anomalous point is allowed only if clearly indicated (i.e. circled and labelled) by the candidate. • Lines must not be kinked or thicker than half a small square. 1 P (gradient) is correctly calculated with correct units (cm-1 A-1) and correct significant figures. Gradient: the hypotenuse of the Δ must be greater than half the length of the drawn line. Check for Δy/Δx (i.e. do not allow Δx/Δy). Gradient triangle must be clearly drawn. All coordinates read-off from graph must be accurate to half a small square. 1 Q (y-intercept) is correctly calculated with correct units (A-1) and correct significant figures. y-intercept: Either correct read-off from a point (accurate to half a small square) on the line substituted into y = mx + c, or intercept is read directly from the graph, with read-off accurate to half a small square. 1 2e • R calculated correctly and given to correct units and correct s.f. 1

5 ©EJC 2023 9749/04/J2H2Prelim/2023 [Turn over Qns A