DHS 2025 H2 Prelim P2

@ DHS 2025 9749/02 [Turn over Name: Centre/Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper 9749/02 17 September 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your class, index number and name at the top of this page Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the question paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 5 2 10 3 5 4 11 5 9 6 11 7 9 8 20 s.f. -1 Total 80 This document consists of 21 printed pages and 3 blank pages.

2 @ DHS 2025 9749/02 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 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

3 @ DHS 2025 9749/02 [Turn over Formulae uniformly accelerated motion, s = ut + at2 v2 = u2 + 2as work done on/by a gas, W = pV hydrostatic pressure, p = gh gravitational potential,  = −Gm/r temperature, T/K = T/oC + 273.15 pressure of an ideal gas, p = mean translational kinetic energy of an ideal gas molecule, E = displacement of particle in s.h.m., x = x0 sin t velocity of particle in s.h.m., v = v0 cos t =  electric current, I = Anvq resistors in series, R = R1 + R2 + . . . resistors in parallel, 1/R = 1/R1 + 1/R2 + . . . electric potential, V = alternating current / voltage, x = x0 sin t magnetic flux density due to a long straight wire, B = magnetic flux density due to a flat circular coil, B = magnetic flux density due to a long solenoid, B = radioactive decay, x = x0 exp(−t) decay constant,  = 1 2 21 3 Nm cV  kT2 3 22 xxo − r Q o4 0 2 d I  0 2 N r I 0nI 1 2 ln2 t

4 @ DHS 2025 9749/02 1 (a) (i) Define density. ………………………………………………………………………………......... ………………………………………………………………………………......... [1] (ii) State the base units in which density is measured ………………………………………………………………………………......... [1] (b) The speed v of sound in a gas is given by the expression pv  = where p is the pressure of the gas of density 𝜌. 𝛾 is a constant. Given that p has the base units of kg m−1 s−2, show that the constant 𝛾 has no unit. [3] [Total: 5 marks]

5 @ DHS 2025 9749/02 [Turn over 2 A ball, initially at rest, slides down the roof of a house at a constant acceleration of 5.0 m s−2. It moves through a distance of 4.0 m before dropping off the edge of the roof to the muddy ground and coming to a complete stop upon impact,15.0 m below. The roof slopes downward at an angle of 37.0° as shown in Fig. 2.1. Fig. 2.1 (a) Show that the speed of the ball when it reaches the edge of the roof is 6.32 m s−1. [1] (b) Calculate the horizontal and vertical components of the velocity of the ball just before it lands on the ground. horizontal component of velocity = …………………………………. m s−1 vertical component of velocity = …………………………………. m s−1 [2] 4.0 m 15.0 m 37.0o

6 @ DHS 2025 9749/02 (c) Determine the total time that the ball is in motion. total time = …………………………………. s [3] (d) Sketch labelled graphs to show the variation with time of the (i) magnitude of acceleration a of the ball, [2] (ii) speed v of the ball. [2] [Total: 10] a t v t

7 @ DHS 2025 9749/02 [Turn over BLANK PAGE

8 @ DHS 2025 9749/02 3 (a) Explain how an electric field and a magnetic field may be used for the velocity selection of charged particles. You may draw a diagram if you wish. ……………………………………………………………………………….................. ……………………………………………………………………………….................. ……………………………………………………………………………….................. ……………………………………………………………………………….................. ……………………………………………………………………………….................. ……………………………………………………………………………….................. [3]

9 @ DHS 2025 9749/02 [Turn over (b) The isotopes strontium-87 ( 87 38Sr ) and strontium-86 ( 86 38Sr ) are found in samples of Moon rock. Particles of a sample of Moon rock are vaporised, releasing strontium isotopes that are sent into the velocity selector of a mass spectrometer as shown in Fig. 3.1. The positive ions of strontium isotopes then pass through a uniform magnetic field which makes them follow separate circular paths. Fig. 3.1 The velocity selector allows strontium ions of speed 7.6 × 105 m s−1 to enter the evacuated chamber in uniform magnetic field of magnetic flux density 680 mT. Determine the change in the magnetic flux density needed to make the strontium-87 ( 87 38Sr ) ions follow the same path taken initially by the strontium-86 ions. change in magnetic flux density = …………………………………. T [2] [Total: 5] positive ions of strontium isotopes velocity selector ion detector evacuated chamber in uniform magnetic field path of Sr38 86 ions

10 @ DHS 2025 9749/02 4 Two equally charged conducting spheres with small radii, each of mass m and charge +3.20 × 10−7 C are hung from the ceiling with insulated strings of negligible mass and length 0.50 m as shown in Fig. 4.1. Fig. 4.1 (not to scale) (a) Determine the magnitude of the electric force acting on each sphere. electric force = …………………………………. N [2] (b) Determine the mass m of each sphere. m = …………………………………. kg [2] 3.0° 0.50 m