ACJC H1 PHY P2

This paper consists of 22 printed pages Anglo-Chinese Junior College Physics Preliminary Examination Higher 1 CANDIDATE NAME CLASS CENTRE NUMBER S 3 0 0 4 INDEX NUMBER PHYSICS Paper 2 Structured questions Candidates answer on the Question Paper No additional Materials are required 8866/02 24 August 2016 2 hours READ THESE INSTRUCTIONS FIRST Write your Name and Index number in the spaces provided at the boxes above and on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer any two question. 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. For examiners’ use only Section A 1 / 5 2 / 6 3 / 7 4 / 8 5 / 8 6 / 6 Section B 7 / 20 8 / 20 9 / 20 Total / 80

2 2016 H1 8866 Prelim Exam P2 For Examiner’s Use 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 at 2 v 2 = u 2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p =  g h resistors in series, R = R1 + R2 +  resistors in parallel, 1/R = 1/R1 + 1/R2 + 

3 2016 H1 8866 Prelim Exam P2 [Turn over For Examiner’s Use Section A Answer all the questions in the spaces provided. 1 (a) State the main distinction between a systematic error and a random error in the measurement of a physical quantity. [2] (b) In a simple pendulum experiment to determine g the acceleration due to gravity, the following equation is used, 𝑇 = 2𝜋√ 𝑙 𝑔 The following measurements were obtained with the help of a meter rule and stopwatch respectively. The length of the pendulum: l = 98.0 cm  0.1% Average time for 10 oscillations: t = 19.8 s  1% g was calculated to be 9.869 m s-2. Present the value of g with its associated uncertainty. g = ………….…  .............. m s [3]

4 2016 H1 8866 Prelim Exam P2 For Examiner’s Use 2 (a) State the law of conservation of linear momentum. [2] (b) A bullet of mass 0.02 kg travelling horizontally with a speed of 500 m s -1 becomes embedded in a bag of sand of mass 40 kg initially at rest which is suspended vertically via a rope fixed to the ceiling. Determine the maximum increase in height gained by the sandbag. State your assumptions made. Maximum increase in height = ……………………… m [4]

5 2016 H1 8866 Prelim Exam P2 [Turn over For Examiner’s Use 3 (a) State the two conditions required for a body to be in equilibrium. [2] (b) When you are walking, there is an instant when only one foot is on the ground and the centre of gravity of your body is directly over that foot. Fig. 3.1 shows the forces acting on that leg. Fig. 3.1 The forces are the upward force on the foot equal to the weight of the body W; the weight of the leg WL (which is approximately equal to W / 7); the reaction force by the hip on the femur R and the tension in the muscle group between the hip and the greater trochanter on the femur T. The dimensions provided are in cm. (i) Show that T = 1.6 W and R = 2.4 W. [3] Source: https://medicalphysics.org/ documents/WebPOTB.pdf

6 2016 H1 8866 Prelim Exam P2 For Examiner’s Use (ii) The use of crutches or a cane can reduce the force on the hip joint. Fig. 3.2 shows the effect of the use of a cane on the body. Fig. 3.2 Note that the cane is in the hand opposite to the injured hip and the force pushing upward on the cane FC reduces the upward force on the foot. Explain qualitatively how the cane can reduce the force on the hip joint. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ……………………………………………………………………………………… [2] Source: https://medicalphysics.org/ documents/WebPOTB.pdf

7 2016 H1 8866 Prelim Exam P2 [Turn over For Examiner’s Use 4 Fig. 4 shows two circuit which could be used to act as a dimmer switch for a lamp. Fig. 4 (a) Explain one advantage circuit 1 has over circuit 2. [2] (b) One problem with circuit 1 is that there is always a current in the resistor. With an aid of a diagram, explain how this problem could be rectified. [2]

8 2016 H1 8866 Prelim Exam P2 For Examiner’s Use (c) (i) The lamp is rated at 60 W at 240 V. Calculate the resistance of the lamp filament at its normal operating temperature. resistance =  [2] (ii) State and explain how the resistance of the filament at room temperature would compare with the value calculated in (c)(i). [2] 5 (a) By reference to the photoelectric effect, state what is meant by the thre shold frequency. [1] (b) Electrons are emitted from a metal surface when ligh t of a particular wavelength is incident on the surface. Explain why the emitted electrons have a range of v alues of kinetic energy below a maximum value. [2]

9 2016 H1 8866 Prelim Exam P2 [Turn over For Examiner’s Use (c) The wavelength of the incident radiation is λ. The variation with 1/λ of the maximum kinetic energy EMAX of electrons emitted from a metal surface is shown in Fig. 6.1. Fig. 6.1 Using the data from Fig. 6.1, (i) determine the work function energy .  = J [2] (ii) the associated de broglie’s wavelength of the electron that was emitted with the maximum kinetic energy when a frequency of 7.5 x 1014 Hz falls on the metal. De Broglie’s wavelength = m [3]

10 2016 H1 8866 Prelim Exam P2 For Examiner’s Use 6 The 2 second rule is a rule of thumb by which a driver may maintain a safe following distance at any speed. The idea is that a driver should stay at least two seconds behind any vehicle that is directly in front of the driver's vehicle. To estimate the time, a driver can wait until the rear end of the vehicle in front passes any distinct and f ixed point on the roadway like a road sign, mailbox, line / crack / patch in the road. After the car ahead passes a given fixed point, the front of one's car should pass the same point no less than two seconds later. If the elapsed time is less than this, one should increase the distan ce, then repeat the method again until the time is at least two seconds. Fig. 6.1 below shows the recommended minimum stopping distances, thinking distances and braking distances under normal road conditions for different speeds. Speed (km h-1) Stopping distance (m) Thinking distance (m) Braking distance (m) 30 12.0 5.6 40 18.0 7.5 10.5 50 25.0 9.5 60 33.0 11.3 21.7 80 52.0 15.0 37.0 100 70.0 18.8 120 102.0 22.5 Fig. 6.1 The stop