QSS 2024 4E Physics Prelim P1&2 (Solution)

1 2024 4E Physics Prelim Exam Solution Paper 1 Multiple Choice Questions [40 marks] 1 D 11 A 21 D 31 B 2 C 12 B 22 D 32 A 3 B 13 B 23 C 33 B 4 A 14 C 24 D 34 B 5 A 15 D 25 D 35 B 6 C 16 A 26 C 36 D 7 A 17 C 27 B 37 C 8 C 18 A 28 D 38 D 9 D 19 B 29 B 39 B 10 A 20 B 30 C 40 B Paper 2 Note: Deduct one mark overall for incorrect significant figures. Deduct one mark overall for no unit or incorrect unit. Section A: Structured Questions [70 marks] Qn Solution Mark 1(a) Let 1 cm represent 10 N. - correct vector diagram - resultant force = 140 N (accept 138 N – 142 N) [1] [1] 1(b) 140 = 8.0a a = 17.5 m/s2 [1] 1(c) 017.5 6.0 105 m/s v v −= = [1] 2(a)(i) Moment = 110(0.05) = 5.5 N m (or 550 N cm) [1] [1] 60° 75° 100 N 50 N 140 N 75°

2 2(a)(ii) The perpendicular distance from the line of action of F to B is 8.0 cm, while the perpendicular distance from F to A is zero. Hence the moment of F applied at B will be greater than the moment of F applied at A (which is zero). [1] 2(b) When the boy raises his left foot off the ground, his weight will produce a clockwise moment about his right foot (i.e. the pivot), which causes him to topple. (Note: the rightward horizontal force which the wall initially exerts on the boy’s arm also produces a clockwise moment about his right foot). [1] 3(a) Pressure = 640/(2.0 x 10-4) = 3.2 x 106 Pa [1] [1] 3(b) Pressure exerted by oil on piston B = 3.2 x 106 Pa Force on piston B = (3.2 x 106)(15 x 10-4) = 4800 N [1] [1] 3(c) I do not agree. If the cross-sectional area of cylinder D is less than 2.0 cm2, the force exerted by piston B on the brakes will be less than 4800 N. To produce the same force of 4800 N, the force exerted by the driver’s foot on the brake pedal would have to be much larger, which may not be feasible (Or: the car will take a longer time to come to a stop). [1] [1] 4(a) GPE = (1.2)(10)(7.5) = 90 J [1] [1] 4(b) GPE of ball at max height of 10 m = (1.2)(10)(10) = 120 J By conservation of energy, 120 + 25 = 90 + ½ (1.2)(vo)2 vo = 9.57 m/s [1] [1] [1] 4(c) Air resistance is negligible. (Any other valid answers) [1] 5(a) Depth of sea = speed of sound x time = 1200 x 0.75 / 2 = 450 m [1] [1] 5(b) The sound transmitter causes water particles near it to vibrate to and fro in the direction parallel to direction of wave travel, forming regions of compression and rarefaction , as energy is transferred through the water as longitudinal sound waves. [1] [1]

3 5(c)(i) 5(c)(ii) [1] [1] 6(a) Correct plotting of all points. Correct best fit curve.