2023 VJC Prelim P2 QP

VICTORIA JUNIOR COLLEGE 2023 JC2 PRELIMINARY EXAMINATION Higher 1 Name : __________________________ CT group : ________________ PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 8867/02 20 September 2023 WEDNESDAY 8 am to 10 am (2 hours) READ THESE INSTRUCTIONS FIRST Write your name and Civics Group on all the work you hand in. 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. DO NOT WRITE ON ANY BARCODES. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all questions. Section B Answer any one question. 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 Question Mark Section A 1 2 3 4 5 6 Section B 7 8 Total / 80 This document consists of 27 printed pages and 1 blank page.

2 Data speed of light in free space c = 3.00  108 m s-1 elementary charge e = 1.60  10-19 C 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 the Avogadro’s constant NA = 6.02 × 1023 mol-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) at2 v2 = u2 + 2as resistors in series R = R1 + R2 + … resistors in parallel 1/R = 1/R1 + 1/R2+ …

3 Section A Answer ALL questions from this section H1 P2 - Errors and UncertainƟes SSQ 1 John performs an experiment involving a spring. The unextended length of the spring was measured to be x1 = 10.0  0.1 cm. When a load was placed at the bottom of the vertically suspended spring, it extended to x2 = 20.0  0.1 cm. The spring constant k is known to be 20 N m-1 exactly. (a) State Hooke’s Law. …………………………………………………………………………………………… ………………………………………………………………………………………… [1] (b) Determine a value for the force F exerted on the spring together with its associated uncertainty. F = ( ……………...  ……………. ) N [4] (c) When extended, the spring possesses elastic potential energy given by 2 2 1 1 ( )2U k x x  Calculate a value for the fractional uncertainty of U. Fractional uncertainty = ……………………. [3] [Total: 8]

4 Forces + WEP (H1 P2 SSQ 1) 2 (a) Two identical massless springs and two identical 200 g masses are connected to one another and suspended from a support as shown in Fig. 2.1. The force constant of each spring is 24.0 N m-1. The lower mass is lowered gently until it comes to rest and the system attains equilibrium. Fig. 2.1 (i) Calculate the extension of the upper and lower springs. Extension of upper spring = …………………….. m Extension of lower spring = …………………….. m [3] (ii) Determine the total elastic potential energy stored in the system at equilibrium. Total elastic potential energy stored = …………………………… J [2] P support

5 The system is in a state of equilibrium shown in Fig. 2.1 when the connection between the lower spring and the upper mass breaks at point P , allowing the lower mass to fall away. (iii) Calculate the acceleration of the upper mass at this instant. Acceleration = ………………………. m s -2 [3] (iv) A student wishes to calculate the speed of the upper mass at time t after the break at P using the equation v = u + at where the acceleration is the value found in (iii). Comment on whether his method is correct. ………………………………………………………………………………………. ………………………………………………………………………………………. …………………………………………………………………………………… [2] [Total: 10]

6 H1 P2 - Circular MoƟon SSQ (9m) 3 In the circus, there is an act called the Wheel of Steel. The apparatus consists of two rigid steel circular cages welded to a long steel truss. Two acrobats perform on this apparatus while it is rotating about its centre. The circular cages are 2.0 m in diameter and the truss is 4.0 m long. The acrobats are both 1.8 m tall and have a mass of 80 kg each. We assume that the centre of mass of the acrobats is 0.90 m from the bottom of their feet. Fig. 3.1 (a) In the preparation phase, both acrobats A and B stay within the wheel, while the apparatus rotates at an increasing rate. At one point in the performance, the apparatus rotates with an angular velocity of 1.29 rad s-1 when acrobat B is at the bottom position. Calculate the tangential velocity of B at this instant. Tangential velocity of B = …………………. m s -1 [2] Steel circular cage Steel truss A B A B Centre of rotation 4.0 m 2.0 m 1.8 m

7 (b) In the first trick, the apparatus rotates fast enough until the acrobat A just loses contact with the floor of the cage and seems to be momentarily “weightless” with respect to the cage. (see Fig. 3.2) Fig. 3.2 Calculate the velocity of acrobat A when this happens. Velocity of A = …………………………. m s -1 [3] Hanging in air A

8 (c) In the second trick, the apparatus is spun so fast that acrobat A can stand upside down and be in contact with the top part of the cage. (see Fig. 3.3) Fig. 3.3 Calculate the minimum velocity of acrobat A to accomplish this. Minimum velocity required = …………………….. m s -1 [2] A B

9 (d) The apparatus is rotating at a constant angular velocity in the position shown in Fig. 3.4. Fig. 3.4 In the space below, sketch and label the forces acting on acrobat A. [2] [Total: 9] A B

10 H1 P2 COE/DC SSQ (9m) 4 A battery of unknown e.m.f.  and internal resistance r is connected to two identical resistors R, an ammeter and a voltmeter as shown in the diagram as shown in Fig. 4.1. Fig. 4.1 Shown in Fig. 4.2 are the readings of the voltmeter and the ammeter that were taken as the resistance of both resistors R were increased in an identical manner. Fig. 4.2 R r V R A Current / A 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Voltage / V 0 1.0 5.0 4.0 3.0 2.0 X X X X X X