2024 JPJC H2 Prelim P2 Printed

[Turn over A Data READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, 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. This document consists of 20 printed pages. [Turn over JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2024 PHYSICS 9749/02 Higher 2 27 August 2024 Paper 2 Structured Questions 2 hours Candidates answer on the Question Paper. No Additional Materials are required. Name: _______________________________ Class: ______________ For Examiner’s Use 1 / 6 2 / 8 3 / 6 4 / 10 5 / 10 6 / 9 7 / 11 8 / 20 Total / 80

2 2024/JPJC/Prelim/9749/02 Data speed of light in free space 81000.3 =c m s–1 permeability of free space 7 0 104 −=  H m–1 permittivity of free space 12 0 1085.8 −= F m–1 ( )( ) 910361 −=  F m–1 elementary charge 191060.1 −=e C the Planck constant 341063.6 −=h J s unified atomic mass constant 271066.1 −=u kg rest mass of electron 311011.9 −=em kg rest mass of proton 271067.1 −=pm kg molar gas constant 31.8=R J K–1 mol–1 the Avogadro constant 231002.6 =AN mol–1 the Boltzmann constant 231038.1 −=k J K–1 gravitational constant 111067.6 −=G N m2 kg–2 acceleration of free fall 81.9=g m s–2

3 2024/JPJC/Prelim/9749/02 [Turn over Formulae uniformly accelerated motion 2 2 1 atuts += asuv 222 += work done on/by a gas VpW = hydrostatic pressure ghp = gravitational potential GM r =− temperature / K / C 273.15TT =  + pressure of an ideal gas 21 3 Nmpc V= mean translational kinetic energy of an ideal gas molecule 3 2E k T= displacement of particle in s.h.m. txx sin0= velocity of particle in s.h.m. tvv cos0= 22 0 xx −=  electric current Anvq=I resistors in series ...21 ++= RRR resistors in parallel .../1/1/1 21 ++= RRR electric potential r QV 04= alternating current/voltage txx sin0= magnetic flux density due to a long straight wire 0 2B d  = I magnetic flux density due to a flat circular coil 0 2 NB r = I magnetic flux density due to a long solenoid 0Bn = I radioactive decay )exp(0 txx −= decay constant 1 2 ln2 t =

4 2024/JPJC/Prelim/9749/02 Answer all the questions in the spaces provided. 1 (a) The intensity I of a sound wave moving through a gas is given by 22f A vk=I where f is the frequency of the wave, A is the amplitude of the wave, v is the speed of the wave and k is a constant that depends on the gas. Determine the SI base units of k. SI base units = ........................................ [3] (b) The maximum useful output power P of a car travelling on a horizontal road is given by 3P v b= where v is the maximum speed of the car and b is a constant. For the car, 84 kW 5%P = and 0.56 7%b= in SI units. Determine the absolute uncertainty in the value of v. absolute uncertainty = ........................................ m s−1 [3]

5 2024/JPJC/Prelim/9749/02 [Turn over 2 (a) Fig. 2.1 shows a helicopter of mass 3104.98 kg and carrying a load of 3104.0 kg . It is accelerating vertically upwards at 20.32 m s− . Fig. 2.1 (i) Determine the tension in the cable. tension = ........................................ N [2] (ii) The rotor blades generate a total thrust of 49.1 10 N by imparting a downward velocity v to the air. The length of each rotor blade is 10 m and the density of air is 31.3 kg m .− 1. Show that the mass of air per unit time passing through the rotor is 1410 kg s ,v − where v is in 1m s .− [2] load rotor blades cable

6 2024/JPJC/Prelim/9749/02 2. Calculate the value of v. v = ........................................ m s–1 [2] (b) The helicopter and its load are now travelling horizontally with a constant acceleration. Fig. 2.2 shows the cable making an angle of 65° to the vertical. The air resistance acting on the load is 36.0 10 N . Fig. 2.2 Calculate the magnitude of the acceleration of the helicopter. acceleration = ........................................ m s–2 [2] 65°

7 2024/JPJC/Prelim/9749/02 [Turn over 3 A student attempts to build a cantilever structure in a school laboratory. Using a rigid uniform metre rule of mass 0.11 kg, a uniform block of mass 1.2 kg and several uniform 5.0 g masses, he sets up the cantilever structure shown in Fig. 3.1. Fig. 3.1 (a) (i) Define the moment of a force. .................................................................................................................................. ........................................................................................................................... [1] (ii) Determine the maximum number of 5.0 g masses that he can stack at point X before the structure topples. number of masses = ........................................ [2] 1.2 kg 0.75 m 5.0 g 0.10 m metre rule table X

8 2024/JPJC/Prelim/9749/02 (b) Fig. 3.2 shows the student modifying the structure by adding a string with one end attached to the ceiling and the other end to the centre of the metre rule. Assume that the table surface is rough and no slipping occurs. He then replaces the 5.0 g mass by a load of 1.0 kg. Fig. 3.2 (i) On Fig. 3.2, draw an arrow to indicate the tension acting in the string for the system to be in equilibrium. Label the tension T. [1] (ii) Determine the tension acting in the string if the ruler is just about to topple. tension = ........................................ N [2] 1.0 kg 1.2 kg 0.75 m string pulley 0.10 m table 60°

9 2024/JPJC/Prelim/9749/02 [Turn over 4 (a) Explain why an object moving with uniform speed in a circle must experience a resultant force towards the centre of the circle. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ................................................................................................................................. [2] (b) Fig. 4.1 shows a pendulum bob of mass m, attached to the end of a light rigid rod of length L, moving in a vertical circle at a constant speed v. The rod starts from position