NHHS_2024_sec4_phy_prelim_MS

Marking Scheme for Physics Preliminary Examination 2024 (NHHS) Page 1 of 7 Section A (70 marks) 1 (a) (i) power, energy, current 1 (ii) m, d, k, M, T 1 (b) (i) measuring tape 1 (ii) total mass = 3.45 × 75 / 1000 = 0.259 Mg 1 (iii) appropriate drawing labels + directions of forces resultant = 180 N ± 5% (171 N to 189 N) {ans mark is given only if correct ray diagram is drawn} M1 1 1 2 (a) (i) The gravitational force acting on per kg mass on Mars is 3.7 N. 1 (ii) weight = mg = 25.5 × 3.7 = 94.4 N 1 (b) (i) String A will break. As string B pulled slowly with increasing force, the tension in the string A will not be able to balance the weight and the additional increasing force. 1 1 (ii) String B will break. When string B is pulled with quick and rapid downward force, due to the large mass and hence large inertia, it tends to remain at rest and resist the sudden change in motion. {an explanation in terms of inertia is required} 1 1 3 (a) {An answer indicating the change in the energy store is required} From A to bottom of ramp: GPE s tore decreases and KE store and Internal Energy (heat) store increases. 1 From bottom of ramp to highest point: KE store decreases and GPE store increases. 1 (b) GPE = mgh = 0.80 × 10 × 13.0 = 104 J 1 1 130N 34˚ 45˚ F 180N

Marking Scheme for Physics Preliminary Examination 2024 (NHHS) Page 2 of 7 (c) total energy at A = total energy at final position + heat lost mgh + KE = 104 + 10.7 KE = 104 + 10.7 – (0.8 × 10 × 7.5) = 55 J 1 1 4 (a) manometer 1 (b) (i) pressure = 1.0 × 105 – hρg = 1.0 × 105 – (1.9) (1000) (10) = 81 kPa 1 1 (ii) P0 = Pg + Pm 100 000 = 81 000 + (13 600 x 10 x h) h = 0.14 m 1 1 5 (a) (i) λ = 16.0 / 4 = 4.0 m 1 (ii) v = f λ = 50/60 × 4.0 = 3.3 m/s 1 1 (b) (i) An imaginary line joining all adjacent points that are in phase. 1 (ii) becomes shallower 1 (ii) Waves travel slower in shallower water 1 (c) radio waves microwave infrared red radiation visible light ultraviolet x-ray gamma ray (2 correct – 1 mark) A2 6 (a) Focal length = 6.0 cm – 7.5 cm. (based on student’s ray diagram) M1 M1 1 (b) (i) Image will be further away from the lens and more magnified. 1 (ii) Image will be dimmer. 1 P Q P Q’ F correct ray diagram arrows + dotted lines

Marking Scheme for Physics Preliminary Examination 2024 (NHHS) Page 3 of 7 7 (a) Drawing of positive charges at the top of foil and equal number of negative charges at the bottom of foil 1 (b) charging by induction mentioned Negative charges are repelled to the bottom of foil leaving the positive charge at the top of foil. 1 1 (c) The foil will be attracted to the rod and wi