HCI 2024 H2 Physics Paper 4 Solutions

This paper consists of 24 printed pages, including 3 BLANK pages. HWA CHONG INSTITUTION C2 Preliminary Examination Higher 2 CANDIDATE NAME Suggested Solutions CT GROUP 23S TUTOR NAME PHYSICS Paper 4 Practical Candidates answer on the Question Paper. No Additional Materials are required. 9749/04 22 August 2024 2 hours 30 mins INSTRUCTIONS TO CANDIDATES Write your name, CT group and tutor’s name in the boxes at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Answer all questions. You will be allowed a maximum of one hour to work with the apparatus for Questions 1 and 2, and a maximum of one hour for Question 3. You are advised to spend approximately 30 minutes on Question 4. Write your answers in the spaces provided on the question paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Give details of the practical shift and laboratory, where appropriate, in the boxes provided. At the end of the examination, submit sets A, B and C separately. The number of marks is given in brackets [ ] at the end of each question or part question. Shift Laboratory For Examiner’s Use 1 / 12 2 / 9 3 / 22 4 / 12 Total / 55 A

2 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 BLANK PAGE

3 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 1 In this experiment, you will investigate the period of torsional oscillations of a suspended disc with loaded mass. (a) Set up the apparatus as shown in Fig. 1.1. Fig. 1.1 Disc A and disc B have three small holes spaced at regular intervals near the edge. Pieces of string have been threaded through the holes. Clamp disc B horizontally using two small blocks of wood. Use the clips on disc B to adjust the length l of each string until l is about 100 cm. Place a 50 g mass in the centre of disc A. clips l stand disc B disc A

4 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 (b) (i) Gently rotate disc A through a small angular displacement and release it so that the disc performs torsional oscillations of period T in a horizontal plane as shown in Fig. 1.2. Determine and record T. T = ……………………………………………….. [2] Top View 50 g mass disc A Fig. 1.2 For n = 20 oscillations, t1 = 20.0 s t2 = 20.2 s T = 𝑡1+𝑡2 2𝑛 = 20.0+20.2 40 = 1.01 s (3 s.f.) • Repeated readings of timings t shown • Calculate T with working

5 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 (ii) Repeat (b)(i) for different values of mass m, by stacking the slotted masses on top of each other, until you have five sets of readings of T and m. Present your results clearly. m / g No. of oscillations n Timing for n oscillations T / s lg (m / g) lg (T / s) t1 / s t2 / s 50 20 20.0 20.2 1.01 1.70 0.002 100 30 24.7 24.9 0.827 2.000 -0.083 150 30 21.5 21.4 0.715 2.176 -0.146 200 30 20.0 20.0 0.667 2.301 -0.176 250 35 21.8 22.1 0.627 2.398 -0.234 [4] • 5 sets of readings • Timing t ≥ 20 s • Column headings: Each column heading must contain a quantity, a unit and a separating mark where appropriate. The presentation of quantity and unit must conform to accepted scientific convention • Correct precision for raw data and s.f for calculated data •

6 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 (c) It is suggested that T and m are related by the expression: = nT km where k and n are constants. Plot a suitable graph to determine the values of k and n. [6] Since lg T = n lg m + lg k By plotting a graph of lg T vs lg m, a straight line graph should be obtained with gradient = n and y-intercept = lg k From graph plotted, Gradient of graph = −0.015−(−0.193) 1.770−2.310 = -3.3296 = -3.30 (3 s.f) (-0.015) = -3.3296 (1.770) + y-intercept y-intercept = 0.5684 Hence n = -3.30 lg k = 0.5684 k = 3.70 s g-n = 3.70 s g3.30

7 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 • Axes: • Sensible scales must be used, no awkward scales (e.g. 3:10). • Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. • Scale markings should be no more than two large squares apart • Plotting of points: All observations in the table must be plotted on the grid. Points must be plotted to an accuracy of half a small square. (3 points were checked) • Line of best fit: Judge by balance of all points on the grid about the candidate’s line. 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. • Coordinates of Gradient: The hypotenuse of the triangle used must be greater than half the length bounded by the two extreme points. Both read-offs must be accurate to half a small square in both the x and y directions. • (1.770, -0.015) (2.310, -0.193)

8 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 2 In this experiment, you will investigate the energy stored in a stretched rubber band. (a) (i) Place the rubber band on the bench so that it is taut without being stretched, as shown in Fig. 2.1. The length of the rubber band is 0.L Fig. 2.1 Measure and record 0L for your rubber band. 0L = …………………………………………. [1] (ii) Use the dimensions given on the card to calculate the volume V of the rubber band. V = …………………………………………… [1] • Value of L0 in the range 7.0 cm to 8.0 cm & (to nearest 0.1 cm or 0.001 m) 7.5 cm • Correct calculation of volume V (e.g. 2 x L0 x w x h) (Where w is the width and h is the height of rubber band.) w = 1.5 mm , h = 1.5 mm V = (2 x 7.5 x 10-2 x 1.5 x 10-3 x 1.5 x 10-3) 3.4 x 10-7 m3 / 0.34 cm3

9 Hwa Chong Institution 9749 / 04 / C2 Preliminary Examination 2024 F = …………………………………………… N [1] (b) (i) Set up the apparatus as shown in Fig. 2.2 with the mass hanger suspended from the rubber band. Fig. 2.2 The extended length of the rubber band is L. Calculate the extension e of the rubber band where: 0 = - .e L L Record your answer in metres. e = ……………………………………… m The force F acting on the rubbe