2022 AHS Physics Prelim Paper 3

1 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over CLASS CLASS INDEX 4 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over 13 September 2022 1 hour 50 minutes This document consists of 12 printed pages and 2 blank pages Anglican High School Secondary Four Preliminary Examination 2022 S4

2 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over Section A 1 In this experiment, you will investigate the effect of a frictional load on an electric motor. You are provided with: • a 4.5 V power supply, • a small electric motor, • an ammeter, • a voltmeter, • a resistor of resistance 10 Ω, • a switch or plug key, • electrical leads, • a wooden rod, • a piece of Blu-Tack. (a) Set up the circuit shown in Fig. 1.1. Fig. 1.1 Fix the motor to the bench using the piece of Blu-Tack, as shown in Fig. 1.2. Fig. 1.2 (i) With the switch open, record the voltmeter reading V0. V0 = ….………………………………….. [1] (ii) Check that the shaft of the motor is free to spin by rotating it a few times by hand. Close the switch. Record the potential difference V1 across the motor and the current I1 in the circuit. V1 = ….…………………………………….. I1 = ….…………………………………….. [2]

3 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over (iii) Open the switch. Calculate the input power P1 to the motor using the equation shown. P1 = V1 I1 P1 = ……………………………………… [1] (b) Close the switch. Use the wooden rod to press gently on the shaft of the motor, as shown in Fig. 1.3. Fig. 1.3 Press down on the wooden rod until the shaft just stops spinning. (i) Record the potential difference V2 across the motor and the current I2 when the motor is not spinning. V2 = ….…………………………………….. I2 = ….…………………………………….. [1] Open the switch. (ii) Calculate the resistance R of the motor using the equation shown. R = ……………………………………… [1]

4 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over (c) Some of the input energy to the motor in (a)(iii) is wasted as thermal energy in the coil of the motor. The proportion Q of the energy wasted in this way is given by the equation shown. Calculate Q. Q = ……………………………………… [1] (d) A student uses the apparatus shown in Fig. 1.4 to determine the minimum force F that the rod exerts on the shaft of the motor to stop it spinning. Fig. 1.4 Describe how F may be determined using the apparatus in Fig. 1.4. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… ………………………………………………………………………………………………… [2] (e) Suggest a change to the apparatus in Fig. 1.4 so that F can be measured directly. …………………………………………………………………………………………………… ………………………………………………………………………………………………… [1] [Total: 10]

5 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over 2 In this experiment, you will investigate the oscillation of a metre rule with an attached mass. You are provided with • a stopwatch, • a metre rule with a hole at the 2 cm mark, • a half-metre rule, • a cork with an optical pin, • a retort stand, boss and clamp, • a 100 g mass, • some modelling clay The apparatus has been set up for you, as shown in Fig. 2.1. Ensure that the metre rule is not in contact with the cork. Fig. 2.1 (side view) (a) Use the modelling clay to attach the mass to the rule. The bottom edge of the mass should be level with the 34 cm mark of the scale on the right-hand side of the rule. A front view of the arrangement is shown in Fig. 2.2 and a side view in Fig. 2.3. Ensure that the mass is firmly attached to the rule. 34 cm mark modelling clay metre rule mass mass metre rule Fig. 2.2 (front view) Fig. 2.3 (side view) (scale on the right-hand side)

6 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over (b) The distance from the optical pin to the centre of the mass is x as shown in Fig. 2.4. Measure the distance x. x = …………….…………………..……... [1] (c) Displace the metre rule by a small angle. Release the metre rule and allow it to oscillate. Determine an accurate value for the period T of the oscillating metre rule. T = ………………………….……………... [2] (d) Suggest why the metre rule will eventually come to a stop if it is allowed to oscillate freely. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………….…. [1] Fig. 2.4 (front view) base of retort stand retort stand

7 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over (e) Plan A student suggests that T2 is linearly related to x2. Plan an experiment to investigate this relationship. Your plan should include • the quantities that you will keep constant, • a detailed description of how you will perform the investigation, • an indication of how you will achieve the accurate results, • a statement of the graph you would plot to test the relationship, • a sketch of the graph you would obtain if the suggested relationship is correct. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……..……………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………..…………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………..…………………………………………………………..…… ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

8 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over ……………………………………………………………………………………………………… …………………………………………………………..……………………………………..…… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………………………………………………………………………………………….. [6] [Total: 10] Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over

9 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over BLANK PAGE

10 Anglican High School 2022_S4_Prelim_PHY_P3 [Turn over Section B 3 In this experiment, you will investigate the energy stored in a stretched spring. You are provided with: • a spring, • a 50 g mass-hanger and five 50 g masses, • a half-metre rule, • a 30 cm ruler, • a stand, boss and clamp. (a) Measure the length L0 of the unstretched spring, as shown in Fig. 3.1. Give your answer in metres. Fig. 3.1 L0 = ……………………………………… m [1] (b) Set up the apparatus shown in Fig. 3.2. Fig. 3.2 (i) Measure the stretched length L of the spring and determine the extension x of the spring using the equation x = L – L0 L = ……………………………………………… x = ……………………………………………… [2]