2013 JJC H2 Physics P3

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over JURONG JUNIOR COLLEGE 2013 JC2 Preliminary Examination Name Class 12S PHYSICS Higher 2 Structured Questions Candidates answer on the Question Paper. No additional materials are required. 9646/3 16 Sep 2013 2 hour READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name and class in the space provided at the top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use highlighters, glue or correction fluid. Section A Answer every question. 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. For Examiner’s Use Section A 1 2 3 4 5 Section B 6 7 8 Total (This question paper consists of 22 printed pages)

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 2 Data speed of light in free space, c = 3.00  108 m s1 permeability of free space, o = 4  107 H m1 permittivity of free space, o = 8.85  1012 F m1 = (1/(36))  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, me = 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 Formulae uniformly accelerated motion, s = ut + 1 2 at2 v2 = u2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p = gh gravitational potential,  =  Gm r displacement of particle in s.h.m., x = xo sin t velocity of particle in s.h.m., v = vo cos t v = 22() ox x mean kinetic energy of a molecule of an ideal gas E = 3 2 kT resistors in series, R = R1 + R2 + . . . resistors in parallel, 1/R = 1/R1 + 1/R2 + . . . electric potential, V = o Q ε r4 alternating current / voltage, x = xo sin t transmission coefficient, T  exp(2kd) where k = 2 2 8( )mU E h  radioactive decay x = xo exp(-λt) decay constant λ = 1/ 2 0.693 t

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 3 Section A Answer all the questions in this Section. 1 (a) A stone is being thrown from the top of a cliff with a velocity of 20.0 m s-1 at an angle of 60 to the horizontal, as shown in Fig. 1.1. Fig. 1.1 On the axes of Fig. 1.2, draw graphs to represent the variation with time of (i) VH, the horizontal component of the velocity, [1] (ii) VV, the vertical component of the velocity of the stone. Identify your graphs. [3] Fig. 1.2 20.0 m s-1 velocity / m s-1 time/s 20 10 0 -10 -20 1.0 2.0

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 4 (b) Use your answer in (a) to determine the maximum vertical height h. maximum vertical height h = m [2] 2 (a) Distinguish between gravitational potential energy and electric potential energy. [2] (b) A hydroelectric power station has a power output of 2.0 MW when water of density 1000 kg m -3 passes through its turbines at a rate of 1.4 m 3 s-1. The water is supplied from a reservoir which is 750 m above the power station turbines, as shown in Fig.2. Fig. 2 (i) Show that the mass of the water passing through the turbines each second is 1400 kg s-1. [1]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 5 (ii) Calculate the rate of change in gravitational potential energy of the water flowing between the reservoir and the power station turbines. rate of change in gravitational potential energy = J s -1 [3] 3 (a) The first law of thermodynamics may be expressed in terms of the equation U = q + w (i) Identify each of the terms in this equation. [1] (ii) Some solids contract and some solids expand when they melt. Solid which expands on melting Solid which contracts on melting U q w Fig. 3 Complete Fig. 3 with the symbols + or - to indicate the signs of the thermodynamic quantities for each of the two types of solid when the solids melt at constant pressure. [3]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 6 (b) State qualitatively and explain in molecular terms, what happens to the internal energy of a fixed mass of an ideal gas when, separately, (i) the volume is decreased at constant temperature, [2] (ii) the gas is compressed in a thermally-insulated container. [2] 4. (a) State Newton’s law of gravitation and hence show that the gravitational field strength g at a distance R from a point mass M is given by 2R GMg [3]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 7 (b) A neutron star has mass 5.2 x 1030 kg and radius 1.7 x 104 m. (i) Calculate the gravitational field strength at the surface of the star. field strength = N kg -1 [2] (ii) State the assumption made in your calculation in part (b)(i). [1] (iii) Determine the centripetal acceleration of a particle moving in a circular path of radius 1.7 x 104 m and with a period of rotation of 0.21 s. acceleration = m s -2 [2] (iv) The star rotates about its axis with a period of 0.21 s. Use your answer to (i) and (iii) to suggest whether particles on the surface of the star leaves the surface owing to the high speed of rotation of the star. [2]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 8 5 (a) The resistivity of nichrome is 1.50 × 10-6  m. (i) Explain the term resistivity. [2] (ii) Determine the resistance of a nichrome wire of length 1.2 m and cross-sectional area 2.83 × 10-9 m2. resistance =  [1] (b) The nichrome wire in (a) was then used as a potentiometer wire in the circuit shown in Fig. 5.1. Fig. 5.1 The potentiometer circuit was then used to determine the unknown e.m.f. of cell C with internal resistance r. A balance length of 0.050 m was obtained. (i) Determine the unknown e.m.f. of cell C. unknown e.m.f. of cell C = V [2]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 9 (ii) The internal resistance of the 18 V driver cell in the potentiometer circuit was assumed to be negligible. Explain why this assumption is valid. [1] (c) The experimenter was aware that the small balance length obtained in (b) introduced a large uncertainty in the experimental results. Instead of using a single nichrome wire, he decided to place five identical nichrome wires across the two junctions as shown in the circuit in Fig 5.2. A new balance length was obtained. Fig. 5.2 (i) Show that the new resistance of the potentiometer wire is 130 . [1] (ii) Determine the new potential difference across the five nichrome wires. new potential difference = V [1]

JJC 2013 9646/JC2 Prelim P3/2013 [Turn Over 10 (iii) In order to determine the internal resistance r of cell C, another resistor of 6.0  was connected across cell C as shown in the circuit in Fig 5.3. Fig. 5.3 The new balance length obtained after adding the 6.0  resistor was 0.10 m. Determine the internal resistance r of cell C. internal resistance r =  [2]