AHS 2025 Physics P3 MS

2025 Physics Prelim Practical Exam Mark Scheme Q1(minus 1 mark maximum for precision, unit and sf respectively) (a) (i) VT = 11.5 cm3 [1] (to nearest 0.5 cm3 and between 9.0 to 15.0 cm3) (ii) V1 = 1.92 cm3 [1] ((a)(i) ÷ 6 with correct unit and sf) (b) (i) l = 15.0 cm [1] (in cm ± 0.2 cm from supervisor value to the nearest 0.1 cm) (ii) D = 2.1 cm [1] (± 0.3 cm to the nearest 0.1 cm) (iii) d = 0.53 cm [1] ((b)(ii) ÷ 4 with correct unit and sf) (iv) correct use of set squares at each end lined up with rule or correct diagram accept: reject: (v) V2 = 3.3 cm3 [2] (correct calculation, answer in cm3 and rounded off to 2 s.f.) (c) Any 2: • air bubbles in the straw in method 1 • internal volume is smaller than external volume • straw became squashed / damaged • small amount of water may remain in the straw • water sticks to the finger • some water falls out during transfer in method 1 • straw not completely filled ● the measuring cylinder is not dry / there is some water in the measuring cylinder D D or D Set squares may go under the straw

Q2 (minus 1 mark maximum for precision, unit and sf respectively) (a) L = 16.5 cm [1] (to nearest 0.1 cm) (actual values may vary) (b) It is difficult to determine the centre of the adhesive putty as the putty is not uniform. OR: It is difficult to determine the centre of the spring as the adhesive putty is covering it. Reject: the rod is not vertical Reason: The ruler used to measure L need not be vertical. (c) Any 1: ● there is a weight / weights placed on each base ● bosses are attached as low as possible ● d is not too large / the spring is not too stretched (d) Show evidence of at least 5 oscillations and repeating the experiment twice to obtain the average reading. [1] T = 0.785 s [1] (correct unit & s.f.) Example: Average time for 5 oscillations = 3.94 + 3.91 / 2 = 3.93 s. T = 3.93 / 5 = 0.785 s (e) Planning 1 m for each of the 5 bullet points: 1. Identify d and L to be kept constant respectively for 2 experiments [1] 2. Includes taking average timing and repeating for 5 different sets of values (specify by how much) (Plot a graph of dv against iv is marked together with bullet 3) 3. Sketch both graphs correctly (correct shape and axes). [1] 4. Value of a correctly explained in both experiments. [1] *If student only performs one experiment, the maximum mark is 2 out of 4. 5. Explanation for precaution: any one of the following [1] (i) View the oscillation of the rod from above and use the middle of the oscillation (fiducial marker). This is to determine accurately the start and end of an oscillation. (ii) Take the time taken for 5 / 10 oscillations to reduce error due to human reaction time. (iii) Take average readings to reduce unpredictable error. (iv) The amplitude / angle of o