DHS 2021 JC1 Promos Physics (Paper 2)

1 © DHS 2021 9749/02 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Promotional Examination Year 5 H2 PHYSICS Paper 2 Structured Questions 9749/02 6 October 2021 2 hours READ THESE INSTRUCTIONS FIRST Write your class, index number and name at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the question paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Paper 1 MCQ 20 Paper 2 1 10 2 11 3 9 4 10 5 10 6 10 7 20 s.f. -1 Total 100 This document consists of 19 printed pages and 1 blank page.

2 © DHS 2021 9749/02 [Turn over Data speed of light in free space, c = 3.00 × 108 m s−1 permeability of free space, µo = 4π × 10−7 H m−1 permittivity of free space, εo = 8.85 × 10−12 F m−1 = (1/(36π)) × 10−9 F m−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, m e = 9.11 × 10−31 kg rest mass of proton, mp = 1.67 × 10−27 kg molar gas constant R = 8.31 J K −1 mol−1 the Avogadro constant, NA = 6.02 × 1023 mol−1 the Boltzmann constant, k = 1.38 × 10−23 J K−1 gravitational constant, G = 6.67 × 10 −11 N m2 kg−2 acceleration of free fall, g = 9.81 m s−2

3 © DHS 2021 9749/02 [Turn over Formulae uniformly accelerated motion, s = ut + 1 2 at2 v2 = u 2 + 2as work done on/by a gas, W = p∆V hydrostatic pressure, p = ρgh gravitational potential, φ = −Gm/r temperature, T/K = T/oC + 273.15 pressure of an ideal gas, p = 21 3 Nm cV <> mean translational kinetic energy of an ideal gas molecule, E = kT2 3 displacement of particle in s.h.m., x = x0 sin ωt velocity of particle in s.h.m., v = v 0 cos ωt = ±ω 2 2x xo − electric current, I = Anvq resistors in series, R = R1 + R2 + . . . resistors in parallel, 1/R = 1/R 1 + 1/R2 + . . . electric potential, V = r Q oπε4 alternating current / voltage, x = x0 sin ωt magnetic flux density due to a long straight wire, B = 0 2 d Iµ π magnetic flux denxity due to a flat circular coil, B = 0 2 N r Iµ magnetic flux density due to a long solenoid, B = 0nIµ radioactive decay, x = x0 exp(−λt) decay constant, λ = 1 2 ln2 t

4 Answer all the questions. 1 Two trains, P and Q, travel by the same route, from rest at station A to rest at station B. Train P has a constant acceleration a for the first third of the time , constant velocity for the second third, and constant deceleration of magnitude a for the final third of the time. Train Q has a constant acceleration a for the first third of the distance , constant velocity for the second third, and constant deceleration of magnitude a for the final third of the distance. (a) On the axes of Fig. 1.1, complete the graph to show the variation with time t of the velocity v for train P. The first third of the journey has been drawn. [2] (b) The first third of the journey for train Q has been drawn in Fig. 1.2. © DHS 2021 9749/02 [Turn over tP v t 0 atP Fig. 1.1 tQ v t 0 atQ Fig. 1.2

5 © DHS 2021 9749/02 [Turn over (i) Write down an expression for 1. the distance for each third of the journey in terms of a and tQ, distance = ……………………………………… [1] 2. the duration for second third of the journey in terms of t Q. duration = ……………………………………… [1] (ii) On the axes of Fig. 1.2, complete the graph to show the variation with time of the velocity v for train Q. [2] (c) Hence, determine the following ratio total time taken by train Q for the jour ney total time taken by train P for the jour ney . ratio = ……………………………………….. [4]

6 © DHS 2021 9749/02 [Turn over 2 A pile driver is used to drive cylindrical poles, called piles, into the ground so that they form the foundations of a building. Fig. 2.1 shows a possible arrangement for a pile driver. The hammer is held above the pile and then released so that it falls freely under gravity, unti l it strikes the top of the pile. (a) The hammer has a mass of 250 kg and falls 4.50 m before striking the pile. After impact, the hammer and pile move downwards together. Calculate (i) the speed of the hammer just before the impact, speed of hammer = …….………………… m s −1 [2] (ii) the momentum of the hammer just before the impact, momentum of hammer = …….………………… kg m s −1 [1] Fig. 2.1 pile hammer 4.50 m

7 © DHS 2021 9749/02 [Turn over (iii) the speed of the hammer and pile immediately after impact, if the mass of the pile is 2000 kg. speed of hammer and pile = …….………………… m s−1 [2] (b) After impact, the hammer and the pile move so that the pile sinks into the ground to a depth of 0.25 m. Calculate (i) the loss in kinetic energy of the hammer and pile, loss in kinetic energy = …….………………… J [2] (ii) the average frictional force the ground exerts on the pile while bringing it to rest. average frictional force = …….………………… N [2] (c) The process is repeated several times and each time the hammer is raised 4.5 m above the pile. Suggest why the extra depth of penetration is likely to decrease with each impact. …………............…………………………………………………….…………………………… …………............…………………………………………………….…………………………… …………............…………………………………………………….……………………….. [2]

8 © DHS 2021 9749/02 [Turn over 3 (a) Explain what is meant by centre of gravity. …………............…………………………………………………….…………………………… …………............…………………………………………………….……………………….. [1] (b) Fig. 3.1 shows a supermarket trolley. The weight of the trolley and its contents is 160 N. P and Q are the resultant forces that the ground exerts on the rear wheels and front wheels respectively. Calculate (i) force P, P = …….………………… N [2] (ii) force Q, Q = …….………………… N [2] Fig. 3.1 (not to scale) front wheels rear wheels Q P centre of gravity A 10 cm 40 cm 50 cm

9 © DHS 2021 9749/02 [Turn over (iii) the minimum force that needs to be applied vertically at A to lift the front wheels off the ground. minimum force = ……………………. N [2] (c) State and explain, without calculation, how the minimum force that needs to be applied vertically at A to lift the rear wheels off the ground compares to the force you have calculated in (b)(iii). …..........…………………..………………………………………………………………………. …..........…………………..………………………………………………………………………. …..........…………………..………………………………………………………………………. …..........…………………..………………………………………………………………………. ..….…..........…………………..………………………………………………………………[2]

10 © DHS 2021 9749/02 [Turn over 4 (a) Explain what is meant by gravitational field. .........……………………..………..……………………………………………………………... .........……………………..………..…………………………………………………………... [1] (b) A binary star system consists