October 2021 AS Level Physics A H156/02 Depth in physics Time allowed: 1 hour 30 minutes INSTRUCTIONS • Use black ink. You can use an HB pencil, but onl y for graphs and diagrams. • Write your answer to each question in
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October 2021 AS Level Physics A H156/02 Depth in physics Time allowed: 1 hour 30 minutes INSTRUCTIONS • Use black ink. You can use an HB pencil, but onl y for graphs and diagrams. • Write your answer to each question in the space provided. If you need extra space use the lined pages at the end of this booklet. The question numbers must be clearly shown. • Answer all the questions. • Where appropriate, your answer should be supported with working. Marks might be given for using a correct method, even if your answer is wrong. INFORMATION • The total mark for this paper is 70. • The marks for each question are shown in brackets [ ]. • Quality of extended response will be assessed in questions marked with an asterisk (*). • This document has 20 pages. ADVICE • Read each question carefully before you start your answer. Answer all the questions. 1 Two loudspeakers S1 and S2 are connected to a signal generator. The loudspeakers emit coherent sound waves. (a) State what is meant by the term coherent. ................................................................................................................................................... .............................................................................................................................................. [1] (b) A microphone is connected to an oscilloscope. The points O, J, K and L all lie on a straight line as shown. The microphone is moved from O to L. L K J S1 O S2 Not to scale A series of maxima and minima is observed between O and L. The microphone records a maximum at O. As it moves towards L, the first minimum is observed at J and the next maximum at K. The distance between S1 and J is 2.00 m and the distance between S2 and J is 2.08 m. The distance between S1 and K is 2.05 m and the distance between S2 and K is 2.21 m. (i) Calculate the path difference at point J between the waves from S1 and S2. path difference = m [1] (ii) State the phase difference in radian at point J between the waves from S1 and S2. phase difference = rad [1] (iii) Show that the wavelength of the sound waves is 0.16 m. [1] (c) The frequency of the sound is determined using the oscilloscope. (i) Explain how the oscilloscope is used to determine the frequency. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (ii) The frequency of the sound is 2.1 kHz. Determine the speed v of sound. v = m s−1 [2] 2 (a) The force F against extension x graph below shows the loading and unloading of a piece of rubber. 15 F / N 10 5 0 0 0.05 0.10 0.15 0.20 0.25 0.30 x / m (i) State the physical quantity represented by the area under the loading curve. ...................................................................................................................................... [1] (ii) Determine the energy E transferred when the rubber is stretched to an extension of 0.25 m. E = J [2] (iii) Suggest why the energy transferred by the rubber during unloading is different to your answer in (ii). ........................................................................................................................................... ...................................................................................................................................... [1] (b) A metal wire has length 2.2 m and cross-sectional area of 1.4 × 10−7 m2. One end of the wire is fixed to the ceiling and a load of weight 49 N is attached to the other end so that the wire is vertical. The Young modulus of the metal is 180 GPa. The wire obeys Hooke’s law. Calculate (i) the stress σ in the wire σ = Pa [2] (ii) the strain ε of the wire ε = [2] (iii) the extension x of the wire x = m [2] (iv) the elastic potential energy E of the wire. E = J [2] (c) The wire in (b) is replaced by a wire of the same metal and length but double the diameter. The same load is attached to the wire. State and explain the change, if any, to the elastic potential energy of the wire. ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] 3 (a)* A linear air track is used to investigate the collision of two gliders A and B, as shown in Fig. 3.1. Fig. 3.1 Light gates 1 and 2 are connected to a data-logger to determine the speed of the gliders. Glider A has a mass of 0.75 kg and glider B has a mass of 1.25 kg. Two experiments are carried out. Experiment 1 • Glider B is initially at rest between light gates 1 and 2. • Glider A passes light gate 1 at a speed of 0.200 m s−1. • Glider A collides with glider B. • Glider A rebounds and passes light gate 1 at a speed of 0.050 m s−1 and glider B passes light gate 2 at a speed of 0.150 m s−1. Experiment 2 • Glider B is initially at rest between light gates 1 and 2. • Glider A passes light gate 1 at a speed of 0.200 m s−1. • Glider A collides with glider B. • Glider A sticks to glider B. • Both gliders pass light gate 2 at a speed of 0.075 m s−1. With the help of calculations and the terms below, explain the results of the two experiments. [6] elastic inelastic momentum
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