SRJC H2 PHY P2

SRJC 2011 9646/Prelim/2011 [Turn Over SERANGOON JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION General Certificate of Education Advanced Level Higher 2 PHYSICS 9646/02 Paper 2 Structured Questions 18 August 2011 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, Civics Group and index number 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. Answer all questions. At the end of the examination, fasten all your work securely together. The number of marks is given in bracket [ ] at the end of each question or part question. This document consists of 18 printed pages and no blank page. For Examiner’s Use 1 2 3 4 5 6 7 8 9 10 Total SERANGOON JUNIOR COLLEGE Science Department Physics Unit CIVICS GROUP CANDIDATE NAME INDEX NUMBER

2 SRJC 2011 9646/Prelim/2011 DATA AND FORMULAE Data speed of light in free space, c = 3.00  108 m s1 permeability of free space, 0 = 4   107 H m1 permittivity of free space, 0 = 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 + ½ at 2 v2 = u 2 + 2as work done on/by a gas, W = p V hydrostatic pressure, p = gh gravitational potential,  = – r Gm displacement of particle in s.h.m., x = x 0 sin t velocity of particle in s.h.m., v = v o cost v =  22 0 xxω  resistors in series, R = R 1 + R2 + … resistors in parallel, 1/ R = 1/R1 + 1/R2 + … electric potential, V = Q / 4or alternating current/voltage, x = x 0sin t transmission coefficient, T  exp(2kd) where k = 2 2 h E)m(U8 π radioactive decay, x = x0 exp(t) decay constant,  = 2 1 693.0 t

3 SRJC 2011 9646/Prelim/2011 [Turn Over For Examiner’s Use Answer all questions 1 A SRJC student who intends to major in Physics in university attempted to recall Bernoulli’s equation, widely used in the field of fluid dynamics. Based on his recollection during H3 lectures, he was able to come up with the following equation:   1 2 akp h ρg ρv where p is pressure, h is height,  is density, v is velocity and k is a constant. However, he was unable to recall the value of a. (a) Based on dimensional analysis (i.e. comparison of units of terms in the equation), determine the value of a.   avp 21    a mskgmNm 132     aa skgmmkgms   322 [M1] aa skgmskgm   321 By comparing coefficients, a = 2 [A1] a = ........................ [2] (b) Under certain conditions , the equation reduces to  1 2 ak ρv . Calculate the percentage uncertainty in k, given the values of the quantities as listed below. = (1000 ± 2%) kg m-3 v = (20.0 ± 0.2) m s-1 2 21 vk  v v k k  2  [M1] 04.00.20 2.0202.0      Percentage uncertainty = 0.04 x 100% = 4% [A1] percentage uncertainty = ........................ % [2]

4 SRJC 2011 9646/Prelim/2011 For Examiner’s Use 2 (a) Derive, from the definitions of velo city and acceleration, the expression v 2 = u2 + 2as. [2] (b) In an experiment to test the effect of air resistance on different objects, a small stone and a thin piece of st iff cardboard are separatel y projected horizontally from the same vertical height, at the sa me initial speed. The figure below shows the path taken by the stone. The plane of the cardboard remains parallel to the ground during its journey. (i) Explain why the horizontal range cove red by the path of the cardboard is observed to be further than that of the stone. ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ……………………………………………………………………………………..[2] horizontal range by stone path of the stone stiff cardboard ground small stone

5 SRJC 2011 9646/Prelim/2011 [Turn Over For Examiner’s Use (ii) Describe and explain if the final velocity of t he cardboard before hitting the ground is higher, lower or the same, than that for the stone. ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ………………………………………………………………………………………... ……………………………………………………………………………………..[2]

6 SRJC 2011 9646/Prelim/2011 For Examiner’s Use 3 (a) State the Principle of Conservation of Linear Momentum. .................................................................................................................................. ……………………………………………………………………………………………... ……………………………………………………………………………………………[1] (b) Box A, of mass 1.5 kg, s lides down a rough slope with an initial velocity of 2.0 m s1. The vertical height of the slope is 2.5 m and the work done against friction by Box A is 5.0 J. (i) Calculate the velocity of Bo x A at the bottom of the slope. velocity of Box A at bottom of slope = ………………… m s 1 [2] A B 2.0 m s1 2.5 m rough slope smooth surface

7 SRJC 2011 9646/Prelim/2011 [Turn Over For Examiner’s Use (ii) At the bottom of the slope, Box A travels along a smooth surface before colliding elastically with a stationary Box B of mass 3.0 kg. Calculate the final spe eds of Box A and Box B. speed of Box A = …………………….. m s 1 speed of Box B = ..……………………. m s 1 [3]

8 SRJC 2011 9646/Prelim/2011 For Examiner’s Use 4 A tank with an L-shaped pipe is to be used as a weighi ng scale. A light airtight frictionless piston is in the pi pe, and is in contact with t he water. The cross-sectional area of the tank is 4 time s that of the piston. The connecting pipe has negligible volume. Initially, the water levels in the pipe and tank are equal. An objec t is placed gently on the piston and the piston descends to a new height. It is observ ed that the piston descends by 2.0 cm. (a) (i) Calculate the difference in water levels within the pipe and tank. Decrease in volume of water within pipe = Increase in volume of water within tank [M1] Let Cross-sectional area of pipe be A. (2.0 cm) (A) = (Increase in height of water in tank) (4A) Increase in height of water in tank = 0.5 cm Difference in water levels = 2.0 + 0.5 cm = 2.5 cm [A1] difference in water levels = …………………… cm [2] (ii) Hence calculate the mass of the obj ect. The cross-sectional area of the piston is 0.01 m2, and the density of water is