VJC 2022 Prelim P2

1 VICTORIA JUNIOR COLLEGE 2022 JC2 PRELIMINARY EXAMINATIONS Higher 2 Name : __________________________ CT group : ________________ PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9749 / 02 8 – 10 am 2 Hours READ THESE INSTRUCTIONS FIRST Write your name and CT group at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Answer all 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 sf units g Total (max. 80) This question set consists of a total of 16 printed pages.

2 Data speed of light in free space, c = 3.00 × 108 m s-1 permeability of free space, µo = 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 mol-1 K-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 Formulae uniformly accelerated motion, s = ut + (½) at2 v2 = u2 + 2as work done on/by a gas, W = pV hydrostatic pressure, p = gh gravitational potential, GM r =− temperature / / 273.15T K T C=  + pressure of an ideal gas 21 3 Nmpc V= mean translational kinetic energy of an ideal gas molecule 3 2E kT= displacement of particle in s.h.m., x = xo sin  t velocity of particle in s.h.m., 22 cos () o o v v t xx   = =  − electric current I Anvq= resistors in series, R = R1 + R2 + … resistors in parallel, 1/R = 1/R1 + 1/R2+ … electric potential, V = Q/4or alternating current/voltage, x = xo sin  t Magnetic flux density due to a long straight wire 0 2 IB d  = Magnetic flux density due to a flat circular coil 0 2 NIB r = Magnetic flux density due to a long solenoid 0B nI= radioactive decay, x = xoexp(-t) decay constant, 1 2 ln2 t =

4 Answer all questions in the spaces provided 1(a) A massive truck is parked along the roadside on a flat surface. Adam pushes the truck, and it does not move. He justifies this by saying that the two forces that he and the truck exert on each other are equal and opposite, so they cancel out each other. Using Newton’s laws of motion, comment on his explanation and explain why the truck does not move. [4] (b)(i) State the principle of conservation of momentum. [1] (ii) In Figure 1.1 below, an 80 kg man is on a ladder hanging from a balloon that has a total mass of 320 kg (including the basket passenger). The balloon is initially stationary relative to the ground. The man on the ladder begins to climb at 2.5 m s -1 as seen by an observer on the ground. (1) Determine the speed and direction that the balloon moves at. [3] Fig. 1.1

5 (2) The man decides to stop climbing. State the speed of the balloon. [1] 2(a) Figure 2.1 shows a light spring of a spring constant k = 160 N m -1 rests vertically on the bottom of a large beaker of water. A 5.0 kg block of wood, with a density of 650 kg m-3, is connected to the spring, and the block-spring system is allowed to come to a static equilibrium. The block of wood has two -thirds of its vo lume partially submerged in the water. Density of water is 1000 kg m-3. (i) Using the figure below, draw and label clearly all the forces exerting on the block of wood. [2] (ii) Determine L. [3] L Figure 2.1

6 (b) A 1200 N uniform boom AC is supported by a cable perpendicular to the boom as shown in Figure 2.2. The cable joins the boom at point B where BC = AC 4 . The boom is hinged at the bottom, and a 2000 N weight hangs from its top. (i) Determine the tension in the supporting cable. [3] (ii) Explain why the force acting on the boom at the hinge is not vertical. [2] 25° 65° 2000 N A B C Figure 2.2

7 3. 350 g of liquid water at 100 oC is turned into steam at 100 oC at an atmospheric pressure of 1.0 x 105 Pa. [Density of water = 1000 kg m-3; Mass of one mole of water molecules = 18 g; Specific latent heat of vaporisation of water = 2.26 x 106 J kg-1] (a) Assuming that the steam behaves like an ideal gas, calculate its volume. [3] (b) Calculate the work done by the steam as it expands against the atmosphere. [3] (c) Calculate the increase in internal energy of the liquid water as it turns into steam. [3] (d) State the form of energy that the increase in internal energy takes. [1]

8 4(a) A small ball rests at point P on a curved track of radius r, as shown in Fig 4.1: The ball is moved a small distance to one side and is then released. The horizontal displacement x of the ball is related to its acceleration a towards P by the expression gxa r=− where g is the acceleration of free fall. (i) Explain why the ball will undergo simple harmonic motion. [2] (ii) The radius r of curvature of the track is 28 cm. Determine the time interval  between the ball passing point P and then returning to point P. [3] Fig 4.1 x P curved track, radius r

9 (b) The variation with time t of the displacement x of the ball in (a) is shown in Fig 4.2. Some moisture now forms on the track, causing the ball to come to rest eventually. On the axes of Fig 4.2, sketch the variation with time t of the displacement x of the ball for the first two periods after the moisture has formed. Assume the moisture forms at t = 0. [2] 5. The pick-up on an electric guitar produces an electrical signal from the vibrations of the guitar strings. The pick-up consists of a small coil of insulated wire wound round a small cylindrical magnet as illustrated in Fig. 5.1. Fig. 5.1 The strings of the electric guitar are made of steel. When a string vibrates, an electrical signal is generated between the terminals of the coil. (a)(i) State Faraday’s law of electromagnetic induction. [1] Fig 4.2

10 (ii) Use Faraday's law to explain why an electric signal is generated between the terminals of the coil. [3] (iii) Suggest why nylon strings cannot be used for an electric guitar. [1] (b) Consider a guitar string which is stretched between two fixed clamps 64.0 cm apart. The wire is set vibrating at its fundamental (lowest) frequency and the speed of the waves propagating along the string is 300 m s−1. Show that the string is vibrating at a frequency of 230 Hz. [2]