YJC H1 PHY P2 Solutions

1 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEG E YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE YISHUN JUNIOR COLLEGE Candidate’s Name …………………………………………. CTG ………….… YISHUN JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATIONS 2016 PHYSICS 8866/2 HIGHER 1 19 August 2016 Paper 2 Friday Structured Questions 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name and CTG in the spaces provided above. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all questions. Section B Answer any two questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. This question paper consists of 21 printed pages. Paper 2 Section A Q1 /5 Q2 /11 Q3 /6 Q4 /6 Q5 /6 Q6 /6 Section B Q7 /20 Q8 /20 Q9 /20 Penalty Total /80 % Parent’s Signature …………………..

2 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 Data speed of light in free space, c = 3.00  108 m s-1 elementary charge, e = 1.60  10-19 C the Planck constant, h = 6.63  10-34 J s unified atomic mass constant, u = 1.66  10-27 kg rest mass of electron, me = 9.11  10-31 kg rest mass of proton, mp = 1.67  10-27 kg Acceleration of free fall g = 9.81 m s-2 Formulae uniformly accelerated motion, s = ut + 2 1 at2 v2 = u2 + 2as work done on/by a gas, W = p  V hydrostatic pressure, p =  g h resistors in series, R = R1 + R2+………. Resistors in parallel, R 1 ........11 21  RR =

3 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 Section A Answer all the questions in this section. 1 A student times the fall of a small metal ball. Data for the time t taken for the ball to fall through a vertical distance h from rest are given below. h = (348 ± 1) cm t = (0.842 ± 0.001) s Use these data to determine (a) the acceleration of free fall, g to five significant figures. g = ……………………………….. m s−2 [2] (b) the value of g and its uncertainty, to an appropriate number of significant figures. g = ……………………………… ± ……………………….. m s−2 [3] h = 1 2 g t2 g = 2 h t 2 = 2 × 3.48 × 10−2 0.8422 [1] = 9.8171 m s-2 [1] ∆ g g = ∆ h h + 2 ∆ t t ∆ g 9.8171 = 1 348 + 2× 0.001 0.842 [1] ∆ g = 0.0052489 = 0.006 s (round up to 1 S.F) [1] g = 9.817 ± 0.006 s (round off to same d.p as error) [1]

4 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 2 The graph of Fig 2.1 shows the variation with time t of the velocity v of a ball from the moment it is thrown with velocity v of 26 m s1 vertically upwards. Fig. 2.1 (a) State the time at which the ball reaches its maximum height. time = ………….………. s [1] (b) Just after the ball leaves the thrower’s hand, it has a downward acceleration of approximately 20 m s2 which is much larger than g. Explain how this is possible. .................................…………………………………………………………….………… .................................…………………………………………………………….………… ...................................…………………………………………………………...…… [2] -20 -10 0 10 20 30 0 1 2 3 4 5 v / m s 1 t / s At max height, v = 0 From the graph, t = 1.8 s when v = 0. Downward drag force due to air resistance is acting on it. [1] The resultant force which equals to the sum of the weight and the drag force is larger than the weight. [1] Hence the acceleration is larger than g.

5 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 (c) It is found that the acceleration at t = 1.8 s is g. Explain how this is possible. .................................…………………………………………………………….………… .................................…………………………………………………………….………… ...................................…………………………………………………………...…… [2] (d) Sketch the acceleration-time graph and displacement-time graph in Fig. 2.2 for the motion from t = 0 to t = 4 s, following the sign convention taken for the velocity-time graph in Fig. 2.1. The value of g is marked out in the acceleration-time graph. Label other critical values. [6] Fig. 2.2 a / m s2 t / s  g 4 g 1.8 0 s / m t / s 4 1.8 0 The velocity of object is zero, hence no drag force is acting on it. [1] The resultant force acting on the object equals to the weight [1] Hence the acceleration equals to g. Max 3 marks Curve with decreasing gradient – 1M Shown cutting value of g at t = 1.8 s + labelling of 1.8 s & 4 s – 1M Understanding the sign convention – 1M If drawn cutting the time- axis at any point including t = 4s will have 1M deducted. Max 3 marks Asymmetrical curve skewed towards left – 1M Shown max height at t = 1.8 s + labelling of 1.8 s & 4 s – 1M If graph cuts time-axis at t = 4s will have 1M deducted.

6 8866/YJC/2016/JC2 Preliminary Examinations/Paper 2 3 A light helical spring is suspended vertically from a fixed point, as shown in Fig. 3.1. Different masses are suspended from the spring. The weight W of the mass and the length L of the spring are noted. The variation with the weigh