2024 CHR Physics Prelim ANS

CHR SEC 4 EXP SCIENCE PHYSICS (5086) PRELIM 2024 PROPOSED MARKING SCHEME (FOR TEACHERS ONLY) RESTRICTED 1 Paper 1: Q A Q A Q A Q A Q A Q A Q A Q A 1 A 6 C 11 D 16 C 21 B 26 C 31 B 36 A 2 C 7 D 12 B 17 D 22 A 27 D 32 B 37 B 3 B 8 C 13 B 18 C 23 D 28 B 33 A 38 C 4 B 9 B 14 A 19 D 24 C 29 B 34 D 39 D 5 A 10 D 15 C 20 B 25 A 30 D 35 B 40 C Q Suggested Answer-Concept-Explanation (ACE approach) Marks 1 Answer (A): A Concept (C): Range and precision of instrument Explanation (E): Internal diameter of test-tube -digital calipers Thickness of wire – digital micrometer screw gauge [1] 2 A: C C: Common examples of scalar and vector quantities E: Four vector quantities: i. force, ii. displacement, iii. acceleration, iv. change of velocity [1] 3 A: B Distance travelled = area under speed-time graph [C] = [½ (25 + 20) (10)] + ½ (10) (10) [E] = 275 m [A] Average speed = total distance travelled / total time taken [C] = 275 / 25 [E] = 11 m/s [A] [1] 4 A: B C: Area under speed-time graph =3.0 ½ (5) (t ) = 3.0 [E] t = 1.2 s [A] [1] t speed (m/s) 5.0 t/s

CHR SEC 4 EXP SCIENCE PHYSICS (5086) PRELIM 2024 PROPOSED MARKING SCHEME (FOR TEACHERS ONLY) RESTRICTED 2 5 A: A C: Acceleration of free-fall near earth surface, disregard air resistance E: Constant acceleration [1] 6 A: C C: inertia E: mass is the property that resists change in motion of the body [1] 7 A: D C: Resultant force F = ma FE - 45 - 5 = (4500 + 1000) (0.10) [E] FE = 600 N FBD: Resultant force F = ma [C] T -5 = 1000 (0.1) [E]  T = 105 N Use FBD on the engine to check. [1] 8 A: C Using Principle of Moments, taking moments about P, Sum of CWM = Sum of ACWM [C] F x 0.75 = W x 0.25 [E] W = 3F  F = 1/3 W Total upward force = Total downward force [C] F + P = W P = W – F = W - 1/3 W = 2/3 W Alternatively, take moments about 100 cm mark to arrive at P = 2/3 W [1] 9 A: B; Object with broadest base, lowest CG [E] gives the greatest stability [C] [1] 5 N 45 N T 5N

CHR SEC 4 EXP SCIENCE PHYSICS (5086) PRELIM 2024 PROPOSED MARKING SCHEME (FOR TEACHERS ONLY) RESTRICTED 3 10 A: D Adding weights lower the CG [E] such that the CG is below the pivot for stability. [C] [1] 11 A: D For hydraulic press system, pressure is transmitted from piston X to piston Y. 𝑃𝑥 = 𝑃𝑌; 𝐹𝑥 𝐴𝑥 = 𝐹𝑌 𝐴𝑌 ; 𝐹𝑌=𝐹𝑥 𝐴𝑦 𝐴𝑥 [C] E: reducing diameter of X and increasing the diameter of Y will increase the fo