Pure Physics Nov 2015_TYS ANSWERS

Nov 2015_Suggested ANSWERS_as at July 2023 Page 1 of 7 – Nov 2015 Catholic High School | O-Level Physics NOT IN SYLLABUS: 5059 Nov 2015 P1: - Suggested Answers P2: - Paper 1 [40 marks] 1 C 11 D 21 C 31 C 2 D 12 B 22 A 32 B 3 B 13 A 23 C 33 C 4 D 14 B 24 C 34 D 5 B 15 A 25 A 35 B 6 C 16 B 26 B 36 D 7 D 17 A 27 B 37 C 8 C 18 A 28 A 38 D 9 C 19 B 29 A 39 A 10 D 20 A 30 A 40 D *Q. 1: C Most appeared to be aware of the order of magnitude of the diameter of an atom. Only a significantly smaller proportion were aware of the order of magnitude of the diameter of the Earth. (Both A and B are incorrect.) *Q. 5: B Those who chose D were clearly aware of the effect of air resistance on the velocity of the falling box, but did not convert the increasing magnitude of the velocity to a displacement-time graph of increasing positive gradient. (D is incorrect.) *Q. 7: D In Newton’s Second Law of Motion equation FR = ma, FR is resultant force. The resultant force acting on the car is FR = driving force - frictional force, i.e. FR = driving force - 1200 ma = driving force - 1200 (800)(2.5) = driving force - 1200 Hence, driving force = 2000 + 1200 = 3200 N (A is incorrect.) *Q. 26: B For a converging lens, the rays will bend away from its original direction, towards the principal axis. Also, after passing through the converging, the rays do not necessarily converge to meet (think of magnifying glass). (C is incorrect.) *Q. 34: D When the amount of light increases, the resistance across the LDR decreases. Hence the p.d. across the LDR decreases and the reading on the voltmeter across the resistor increases. (C is incorrect.)

Nov 2015_Suggested ANSWERS_as at July 2023 Page 2 of 7 – Nov 2015 Paper 2 [80 marks] 1 a 1. Using a stopwatch, record t1 and t2: timing for first and second set of 20 complete movements. 2. Calculate tav = 𝑡1+ 𝑡2 2 : average time for 20 complete movements. 3. Calculate t = 𝑡𝑎𝑣 20 : average time for 1 complete movement. 1 1 1 bi The distance moved by the athlete along the track. 1 bii 1. Work done by athlete = (force)(distance along track) (i.e. W = Fd) 2. Power of the athlete = work done by athlete average time for 1 complete movement (i.e. P = 𝑊 𝑡 ) 1 1 2 a When an object is in equilibrium, the sum of clockwise moments about the pivot (/ any point) is equal to sum of anti-clockwise moments about the same pivot (/ same point). 1 1 bi With a 30 N force applied vertically (upwards) at A, the perpendicular distance between the line of action of the force and the pivot is the largest. 1 bii M = Fd = (30)(20) = 600 Ncm or 6.0 Nm ) 1 1 biii Taking moments about the pivot, Clockwise moment by brake cable = Anticlockwise moment by hand-grip 600 = F(1.2) F = M ÷ d = 600 ÷ 1.2 = 500 N (2 or 3 s.f.) 1 3 ai1 p = 𝐹 𝐴 Force that oil exerts on piston P = pA = (3.0 × 105)(5.0 × 10-5) = 15.0 N (3 s.f.) 1 1 ai2