Regent Prelim Ans

Marking Scheme for 4E Physics Prelim 2024 Paper 1 1 C 11 A 21 A 31 B 2 A 12 D 22 B 32 C 3 B 13 D 23 B 33 C 4 B 14 C 24 D 34 D 5 A 15 A 25 C 35 B 6 D 16 B 26 B 36 D 7 C 17 D 27 B 37 D 8 B 18 B 28 B 38 D 9 C 19 D 29 D 39 B 10 A 20 C 30 C 40 C Paper 2 Section A Qn Solution Marks 1(a) Straight line starting from zero, with gradient 10m/s2 B1 (b) a = 1.6 / 0.34 = 4.7(1) accept 4.7 to 5.0 M1 A1 (c) F = ma = 0.035 x 4.705 = 0.165 N 0.350 – 0.165 = 0.19 N (0.185 N) M1 A1 (d) Maximum resistive force is 0.35 N. At terminal velocity, resultant force is zero and object falls at constant speed. Resistive force = weight B1 B1

2(a) Correct shape between R and S Arrows pointing towards S B1 B1 (b) Correct vector drawing base on scale Correct direction of electric force Correct magnitude of electric force. 2.2 x 10-4 N M1 B1 A1 3(a) Anticlockwise moment by bucket = 4 x 1.3 = 5.2 Nm Or Clockwise moment by weight of ladder = 16 x 0.85 = 13.6 Nm 13.6 – 5.2 = 8.4 Nm 8.4 / 0.6 = 14 N L is upwards ( anticlockwise moment) M1 A1 B1 (b) The ladder is more stable if it is placed upright with the wider base at the bottom. (wider base area). The centre of gravity will be lower (below the mid point of the ladder) which also increase its stability. B1 B1 4a The air in the nozzle is moving randomly in high speed. When the air molecules collide with the surface of the washer, it exerts a force. Pressure = force / Area B1 B1 bi Left side higher that right side of manometer. B1 bii (1 – 0.75) x 105 = 13 600 x 10 x h H = 0.18(4) m M1 A1

5a Transverse wave The wave propagate in the direction perpendicular to the direction of the source of vibration. B1 B1 Bi Period = 60 / 45 = 1.33 s ¾ x 1.33 = 1.0 s M1 A1 ii f = 45 /60 = 0.75 Hz V = f  24 = 0.75 x   = 32 cm RS = 16 cm M1 A1 6 (a) 2.4 = 3 x 108 / speed of light in diamond speed of light in diamond = 1.3 x 108 m/s = (1.25 x 108 m/s) M1 A1 (b) sin 48 / sin p = 2.4 p = 18 M1 A1 (c) The critical angle is the angle of incidence, in the optically more dense medium, where the angle of refraction is 90°. B1 (d) Sin -1 (1/ 2.4) = 24.6  = 25  A1 (e) Angle of incidence at Q (58) is bigger than the critical angle of diamond. Light there is total internal reflection. B1 B1 7(ai) V = RI 4.8 = 16 x I I = 0.30 A A1 ii) 6- 4.8 = 1.2 V = RI 1.2 = R x 0.3 R = 4  M1 A1 b) When X decrease, the total resistance across XY in parallel will decrease. B1

Volatge across Z will increase. B1 c When temperature increases, resistance of thermistor decrease. Voltmeter reading will decrease. B1 B1 8(a) 6 half life 125 counts per min B1 B1 (b) Sou