RVHS 2024 J2 H2 Physics Prelim P4 Answers

JC2 Prelims P4 2024 Qns Marking Instructions Skill Mark 1(a)(i) l0 = 2.1 cm (accept 1.9 cm to 2.2 cm) Recording of l0 to the nearest 0.1 cm. MMO 1 1(a)(ii) l1 = 14.1 cm (l1 − l0) = 12.0 cm Calculation of (l1 − l0)to the nearest 0.1 cm MMO 1 1(a)(iii) k = (0.300)(9.81) / 0.120 = 24.5 N m−1 or kg s−2 k calculated correctly with correct units PDO 1 1(b)(i) x = 40.0 cm number of oscillations N = 55 t1 = 21.36 s t2 = 21.41 s tavg = 21.39 s T = tavg / N = 21.385 / 55 = 0.3888 s Total timing > 20 s Show evidence of repeat PDO 1 1(b)(ii) Δt ≈ 0.2 to 0.5 s percentage uncertainty of T = ΔT / T = Δt / t = 0.3 / 21.39 = 1.4% (1sf or 2sf only) PDO 1 1(b)(iii) 2 marks for 6 sets of data without assistance and x > 35 cm 1 mark for column headings correctly labelled 1 mark for raw values to appropriate dp • x to the nearest 0.1 cm • t to the nearest 0.01 s 1 mark for calculated values to appropriate sf PDO 5 1(b)(iv) For graph plotting • 1 mark for axes labelled and appropriate scale used • 1 mark for points plotted correctly • 1 mark for line of best fit For calculation of C and D • 1 mark for linearisation statement • 1 mark for gradient triangle drawn, coordinates recorded to the nearest half square and D calculated with correct units (s2 m−2 or s2 cm−2) • 1 mark for y-intercept calculated and C determined with correct units (s2) ACE 6

1(c) difficult to count the number of oscillations when the frequency is too high / period is too short. MMO 1 1(d) Line W with steeper gradient and not crossing the original line, because it is supposed to have the same y-intercept. ACE 1 1(e) • 1 mark for table heading correct and displaying 2 sets of data for number of springs and period. x and m must be kept constant. Since k is inversely proportional to T, proportionality constant is kT. If k is indeed inversely proportional to T, then kT should remain relatively constant. Its variation should only be caused by uncertainties in k and T. o Example of table: k/Nm−1 n nT1/s nT2/s T/s kT/ Nsm−1 24.5 45 22.95 23.10 0.5117 12.5 12.3 35 23.76 23.72 0.6783 8.34 • 1 mark for calculating the percentage difference of kT • 1 mark for making comparison to percentage uncertainty in T and presenting valid conclusion ACE 3 Total: 21 marks Qns Marking Instructions Skill Mark 2(a)(ii) I = 65.3 mA Value of I in range of 50 mA 80 mAI AND to nearest 0.1 mA with unit. MMO 1 2(b)(i) L = 25.0 cm Value of L in range of 24.5 cm 25 5 cmL. AND to nearest 0.1 cm with unit MMO 1 I = 62.4 mA Value of I in range of 50 mA 80 mAI AND to nearest 0.1 mA with unit. PDO 2(b)(ii) Percentage uncertainty of I = 01 100 0 16 %62 4 . .. = Percentage uncertainty between 0.13% and 0.20%. PDO 1

Qns Marking Instructions Skill Mark 2(c)(i) MMO • Award 1 mark if candidate has successfully collected 8 or more sets of data (t, I) without assistance/intervention.