ACS EXP Prelim 2024 P1 and P2 answers

Y4Exp Physics Prelim 2024 P1 & P2 – Answer scheme Page 1 of 9 Anglo-Chinese School (Independent) PRELIMINARY EXAMINATION 2024 YEAR 4 EXPRESS Physics Answer Scheme Paper 1 1 2 3 4 5 6 7 8 9 10 B C A C B D B D C B 11 12 13 14 15 16 17 18 19 20 D B C A A D C C A B 21 22 23 24 25 26 27 28 29 30 B A B B C A D A D A 31 32 33 34 35 36 37 38 39 40 C B B A C D A A C C Paper 2 Section A Q Part 1 (ai) The velocity-time graph of the car from t = 0 s to t = 1.4 s. Accept students who state 1.4s. A1 (aii) Total displacement = (20 x 1.4) + ½ x (20 + 8.0) x (4.0 – 1.4) Total displacement = 28.0 + 36.4 = 64.4 m Average speed = 64.4 / 4.0 = 16 m/s M1 A1 (b) The velocity-time graph of the car from t = 4.0 s to t = 7.0 s has a negative and constant gradient. (accept 1 mark only) Many different ways of describing the motion: • velocity decreases constantly from 8.0 m/s to 0 m/s. • accept slowing down at a constant rate with a deceleration of 2.67 m/s2./decreasing uniformly from 8.0 m/s to 0 m/s. This means that the car is undergoing a constant deceleration of 2.7 m/s2. B1 B1

Y4Exp Physics Prelim 2024 P1 & P2 – Answer scheme Page 2 of 9 Accept: The car decelerated uniformly from the speed of 8.0 m/s to 0 m/s. At 0 m/s, the car is at rest. Accept: The car decelerated uniformly at a lower rate as compared to time from 1.4 s to 4.0 s. 2 (a) The moment of a force about a pivot is the product of the force F and the perpendicular distance d from the pivot to the line of action of the force. B1 (b) At equilibrium, take moment about the pivot, Sum of anti-clockwise moment = Sum of clockwise moment = 0.472 kg x 10 N/kg x (6.2/100) m = 0.29 Nm 4.72 x 6.2 = 29 Ncm accepted Note: Mass ≠Weight (Hence 0.472 kg≠ 4.72 N) Accept Direction: Downwards B1 M1 A1 (c) ∆F x (1.8/100) = 0.29 (allow e.c.f from (b)) ∆F = 16 N M1 A1 3 (ai) F/(5.0 × 10–5) = 1.2 × 106 Pa F = 60 N M1 A1 (aii) As oil cannot be compressed, the same pressure from piston R will be transmitted equally to piston S. With a larger cross-sectional area for piston S, it will experience a larger force F due to P = F/A. where the PR = PS FR/AR = FS/AS In other words, we can see that PS is a multiplier of PR. This ratio is given by the ratio of AS to AR. This is known as Pascal’s Principle. B1 B1 (b) Since the liquid cannot be compressed, the volume of oil displaced in piston R must be equal to the volume of oil displaced in piston S. AR x dR = AS x dS (5.0 × 10–5 m2) x dR = (1.5 × 10–3 m2) x (0.20/1000 m) x 2 dR = 0.012 m = 1.2 cm = 12 mm Or Principle of Conservation of Energy FR x dR = FS x dS 60 x dR = 1800 x (0.20/1000 m) x 2 dR = 0.012 m {where Fs = P x As = (1.2 × 106 Pa) x (1.5 × 10–3 m2) = 1800N} M1 A1 M1 A1

Y4Exp Physics Prelim 2024 P1 & P2 – Answer scheme Page 3 of 9 60 N : 1800 N 1: 30 Hence (0.20 x 2) x 30 = 12 mm