TJC H1 PHYSICS P2

1 TEMASEK JUNIOR COLLEGE 2015 Preliminary Examination Higher 1 CANDIDATE NAME CIVICS GROUP INDEX NUMBER PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 8866/02 28 August 2015 2 hours READ THESE INSTRUCTION FIRST Write your Civics group, index number and name 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. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all questions. 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 1 2 3 4 5 6 7 8 Total This booklet consists of 26 printed pages.

2 Data speed of light in free space, c = 3.00 x 108 m s-1 elementary charge, e = 1.60 x 10-19 C the Planck constant, h = 6.63 x 10-34 J s unified atomic mass constant, u = 1.66 x 10-27 kg rest mass of electron, me = 9.11 x 10-31 kg rest mass of proton, mp = 1.67 x 10-27 kg acceleration of free fall, g = 9.81 m s-2 Formulae uniformly accelerated motion, s = ut + ½at2 v2 = u2 + 2as work done on/by a gas, W = pΔV hydrostatic pressure, p = ρgh resistors in series, R = R1 + R2 + … resistors in parallel, 1/R = 1/R1 + 1/R2 + …

Section A Answer all the questions in this section. 1 A projectile is launched horizontally from a cliff on a distant planet. Fig. 1.1 below plots the horizontal (x) and vertical (y) positions of the projectile every 0.50 s. Fig. 1.1 (a) State an evidence from the plotted data that the planet’s atmosphere had no significant effect on the motion of the projectile. [1] (b) (i) Draw on Fig. 1.1, the displacement vector of the projectile between points E and F of the motion. Label this vector D. [1] 3

4 (ii) Determine the vertical component of the average velocity of the projectile between points E and F. vertical component of average velocity = m s-1 [2] (c) (i) Using the values of y at E, calculate the acceleration due to gravity on this planet. acceleration due to gravity = m s-2 [2] (ii) Assume that the planet has the same density as Earth. From your answer in (c)(i), state and explain whether the radius of the planet is bigger or smaller than that of the Earth. (Given that acceleration due to gravity,  2 Mg r where M is the mass of Earth and r is the radius of Earth.) [2] (d) Another projectile is fired at half the speed of the first one. On Fig 1.1 , plot the positions of this projectile for time intervals of 0.50 s. [2]

5 2 (a) Distinguish between the moment of a force and the torque of a couple. moment of a force torque of a couple [2] (b) One type of weighing machine, known as a steelyard, is illustrated in Fig. 2.1. The two sliding weights can be moved independently along the rod. With no load on the hook and the sliding weights at the zero mark on the metal rod, the metal rod is horizontal. The hook is 4.8 cm from the pivot. A sack of flour is suspended from the hook. In order to return the meta l rod to the horizontal position, the 12 N sliding weight is moved 84 cm along the rod and the 2.5 N weight is moved 72 cm. (i) Calculate the weight of the sack of flour. weight = N [2] Fig. 2.1.

6 (ii) Suggest why this steelyard would be imprecise when weighing objects with a weight of about 25 N. [1]

7 3 (a) The variation with thermodynamic temperature T of the resistance R of a thermistor is shown in Fig. 3.1. Fig. 3.1

8 Suggest, with a reason, why the thermistor, used as a thermometer, is more appropriate for measuring temperatures in the range 273 K to 293 K than in the range 353 K to 373 K. [2] (b) The thermistor is connected into the circuit of Fig. 3.2. Fig. 3.2 The voltmeter connected between A and B has infinite resistance. The battery has e.m.f. 6.00 V and negligible internal resistance. The resistors each have a resistance of 1200 . (i) Determine the thermodynamic temperature at which the voltmeter reads zero. Explain your working. temperature = K [3]

9 (ii) The temperature of the thermistor is now changed to 282 K. Determine the voltmeter reading. State whether A or B has the higher potential. voltmeter reading = V higher potential [4]

10 4 A coil of wire consisting of two loops is suspended from a fixed point as shown in Fig. 4.1. Each loop of wire has diameter 9.4 cm and the separation of the loops is 0.75 cm. The coil is connected into a circuit such that the lower end of the coil is free to move. (a) Explain why, when a current is switched on in the coil, the separation of the loops of the coil decreases. [3] (b) Each loop of the coil may be considered as being a long straight wire. In SI units, the magnetic flux density B at a distance x from a long straight wire carrying a current I is given by the expression When the current in the coil is switched on, a mass of 0.26 g is hung from the free end of the coil in order to return the loops of the coil to their original separation. Calculate the current in the coil. current = A [3] Fig. 4.1 x IB 7100.2 