IJC H1 PHY P2 Solution

© IJC 2016 8866/02/Prelim/16 [Turn over INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION in preparation for General Certificate of Education Advanced Level Higher 1 CANDIDATE NAME CLASS GROUP: PHYSICS Paper 2 Structured Questions 8866/02 23 August 2016 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, 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. Please write down your answers in the spaces provided. The number of marks is given in the brackets [ ] at the end of each question or part question. Marks will be deducted for using inappropriate number of significant figures or wrong value of g. This document consists of 26 printed pages. For Examiner’s Use Section A 1 7 2 5 3 6 4 7 5 5 6 10 Section B 7 20 8 20 9 20 Significant Figures Total 80 Innova Junior College [Turn over

2 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use Data speed of light in free space, c = 3.00 x 108 m s-1 elementary charge, e = 1.60 x 10-19 C the Planck constant h = 6.63 × 10-34 J s unified atomic mass constant, u = 1.66 x 10-27 kg rest mass of electron, me = 9.11 x 10-31 kg rest mass of proton, mp = 1.67 x 10-27 kg acceleration of free fall, g = 9.81 m s-2 Formulae uniformly accelerated motion, s = ut + ½at2 v2 = u2+ 2as work done on/by a gas, W = pV hydrostatic pressure, p = gh resistors in series, R = R1 + R2 + … resistors in parallel, 1/R = 1/R1 + 1/R2 + …

3 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use Section A Answer all the questions in this section. 1 One end of a spring is fixed to a support. A mass is attached to the other end of the spring. The arrangement is shown in Fig. 1.1. Fig. 1.1 (a) The mass is in translational equilibrium. Explain, with reference to the forces acting on the mass, what is meant by translational equilibrium. There is no net resultant force in all directions. [B1] The weight downwards is equal to the tension upwards. [B1] …………………………………………………………………………………………. [2] (b) The mass is pulled down and then released at time t = 0. The mass oscillates up and down. The variation with t of the displacement of the mass d is shown in Fig. 1.2. Fig. 1.2 Given that acceleration is directly proportional to displacement, d, state a time in Fig. 1.2 when the mass is in translational equilibrium. 0.2, 0.6, 1.0 s (any one of these values) [A1] time = ……………………. s [1]

4 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use (c) The arrangement shown in Fig. 1.3 is used to determine the length l of a spring when different masses M are attached to it. Fig. 1.3 The variation with mass M of l is shown in Fig. 1.4 below. Fig. 1.4 (i) State and explain whether the spring obeys Hooke’s law. The spring obeys Hooke’s Law. [B1] From the linear/straight line graph, it suggests that the mass is proportional to the extension, hence the applied force (W=mg) is proportional to extension. [B1] …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………...… [2]

5 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use (ii) Show that the spring constant of the spring is 26 N m-1. [2] Use of the gradient of F-x graph (not F = kx) [C1] 𝑘 = (0.40×9.81)−0 (35−20)×10−2 [M1] k = 26 N m–1 [A0]

6 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use 2 In a pile driver, a steel hammerhead with mass 200 kg is lifted 3.0 m above the top of a vertical I-beam being driven into the ground as shown in Fig. 2.1. The hammer is then dropped from rest, driving the I-beam 7.4 cm further into the ground. The vertical railings that guide the hammerhead exert a constant frictional force of 60 N on the falling hammerhead. Fig 2.1 (a) Show that the speed of the steel hammerhead just before it hits the I-beam is 7.55 m s-1. [2] Method 1 By principle of conservation of energy, Total mechanical energy of hammerhead at top (A) = total mechanical energy of hammerhead at point just above the pile (B) + energy dissipated to surrounding PA + KA = PB + KB + Wdissipated mgh + 0 = 0 + ½mv2 + fh [M1- for correct Wdissipated] (200)(9.81)(3)= ½(200)v2+ (60)(3) [M1-for correct PoCOE equation] v = 7.55 m s-1 Method 2 By consideration of the forces acting on hammerhead, taking downwards to be positive, Fnet= W- f = ma a = (200x9.81-60)/200 = 9.51m s-2 [M1-for correct a] v2 = 02 + 2(9.51)(3) [M1-for correct application of kinematics equation] v= 7.55 m s-1 (b) Calculate the change in kinetic energy of the hammerhead when it drives the I-beam further into the ground. change in kinetic energy of hammerhead = final KE – initial KE = 0 - ½(200)(7.55)2 = -½(200)(7.55)2 (M1- for correct determination of change in KE) = Steel Hammerhead I-beam Vertical railings 3.0 m Ground

7 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use -5700.25 = -5700 J change in kinetic energy = ……………………. J [1] (c) The work-energy theorem states that the net work done on an object is equal to the change in kinetic energy of the object. Hence, using the work -energy theorem and your answer to (b), determine the average force, F, exerted by the I-beam on the steel hammerhead. Using WET, Net work done on hammerhead (during contact with I- beam) = change in kinetic energy of hammerhead Net work done on hammerhead = mgd – fd – Fd = (200)(9.81)(0.074)-(60)(0.074) – F(0.074) = -5700 (M1- for correct determination of net work done) F= 79000 N (A1) F = ……………………. N [2]

8 © IJC 2016 8866/02/Prelim/16 [Turn over For Examiner’s Use 3 (a) On Fig. 3.1, sketch and label a displacement -time graph of a wave , showing clearly what is meant by period and amplitude. Fig. 3.1 [B1] for correct labelling of amplitude. [B1] for correct labelling of period. Marks are award only if the corresponding axes label is indicated correctly. [2] (b) Explain why musical instruments that produce low frequency notes are larger in size than those that produce high frequency notes. Lower frequency notes correspond to longer wavelength waves since v = f λ and the speed of the waves is the same in air. [B1] Since the length of the air column in the instrument is usually some fixed multiples of the wavelength of the sound wave for stationary waves to be formed, the instrument has to be longer. [B1] ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ……………………………………………………………………………………………….. ………………………………………………………………………………………… [2] (c) The speed of sound increases as the temperature rises. During a concert, the temperature of a concert hall increases. Musicians playing instruments such as the trumpets and flutes need to adjust the length of their instruments to keep the pitch (frequency) constant. Explain how the length of their instrument s should be