YHSS 4NA Prelim 2022 MS

1 YHSS 4NA Prelims 2022 5105 Paper 1 [20 marks] 1 B 11 D 2 C 12 D 3 D 13 C 4 C 14 A 5 B 15 C 6 B 16 C 7 B 17 C 8 C 18 D 9 D 19 D 10 A 20 B

2 YHSS 4NA Prelims 2022 5105 [Overall just 1 m deducted from Paper 2 for units error] Paper 2 Section A [14 marks] 1 (a) W = mg = (120)(10) = 1200 N (1 m for substitution, 1 m for final answer) [2] (b) By Principle of Moments, 𝐶𝑊𝑀 = 𝐴𝐶𝑊𝑀 (1200)(0.80) = (𝐹)(0.80 + 0.50) 960 = 1.30𝐹 𝐹 = 960 1.30 = 738 𝑁 (1 m for substitution, 1 m for final answer) [2] Total marks = 4 2 (a) 3 x 108 m/s [1] (b) 𝑓 = 𝑣 𝜆 = 3 × 108 0.1 × 10−9 = 3 × 1018 𝐻𝑧 (1 m for correct substitution, 1 m for correct answer) (if prefix not considered, max of 1m) [2] (c) frequency of gamma rays compared to X-rays Higher wavelength of gamma rays compared to X-rays Lower / shorter speed of gamma rays in vacuum compared to X-rays Same / Equal [2] Total marks = 5 3 (a) 𝑅𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 = 3 + (1 4 + 1 4) −1 = 5 Ω (1 m for correct substitution, 1 m for correct answer) [2] (b) 𝐼 = 𝑉 𝑅 = 6 5 = 1.2𝐴 (1 m for correct substitution, 1 m for correct answer) [2] (c) Increase (resistors connected in parallel have a lower effective resistance, thus the current would increase) [1] Total marks = 5

3 YHSS 4NA Prelims 2022 5105 Paper 2 Section B [16 marks] 4 (a) (i) 101.905 s [1] (ii) 𝑎𝑣𝑒𝑟𝑎𝑔𝑒 𝑠𝑝𝑒𝑒𝑑 = 𝑡𝑜𝑡𝑎𝑙 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒 = 5.063 × 103 101.905 = 49.7 𝑚/𝑠 (Allow for ECF from (a)(i)) (1 m for correct substitution, 1 m for correct answer) (1 m awarded if students do not convert km to m, but show workings) [2] (b) 𝑎 = 𝑣 − 𝑢 𝑡 = 55 − 0 7 = 7.86 𝑚/𝑠2 (1 m for correct substitution, 1 m for correct answer) [2] (c) 𝐹 = 𝑚𝑎 = (920)(7.86) = 7230 𝑁 (1 m for correct substitution, 1 m for correct answer) [2] (d) Stopping distance would increase, due to the decreased friction between the tyres and the road/brakes Total marks = 8 5 (a) X marked between 2 and 6 minutes [1] (b) solid state liquid state arrangement of molecules Closely packed in an orderly arrangement Closely packed, disorderly/no long range order movement of molecules Vibrates about a fixed position Slip and slide over each other 1m for each correct description [4] (c) (i) 1 m for every 4 points plotted correctly If students make a mistake for 1 point, can still award 2 m [2] (ii) Curved line of best fit drawn correctly [1]

4 YHSS 4NA Prelims 2022 5105 (iii) The liquid evaporates / Some molecules escape from the surface of the liquid / Any reasonable answer [1] Total marks = 8 6 (a) Neutral Blue [1] (b) (i) 𝑄 = 𝐼𝑡 = (14.2)(5 × 60) = 4260 𝐶 (1 m for correct substitution, 1 m for correct answer) If students show substitution but did not convert time to seconds, to award 1 m. [2] (ii) 𝑃 = 𝐼𝑉 = (14.2)(240) = 3410 𝑊 (1 m for correct substitution, 1 m for correct answer) [2] (iii) 15 A [1] (c) 1. The circuit breaker would trip (when the earth wire touches the neutral wire, current would flow in the earth wire, causing the circuit breaker to trip) 2. The fuse would blow (as the earth wire has a low resistance, a larger than normal current flows in the circuit, causing the current to exceed the fuse rating). 3. Any other logical explanation [Note: The explanations given here are not required to be awarded the marks] [2] Total marks = 8