Cambridge IGCSE Physics 0625 — 2019 Oct/Nov Paper 6 · Variant 1

1 A student determines the weight of a metre rule using a balancing method. Fig. 1.1. shows the apparatus. 50.0 cm mark a b 90.0 cm mark P 0 cm mark metre rule pivot bench Fig. 1.1 (a) • The student places the metre rule on the pivot. • He places the load P, labelled 1.5 N, on the metre rule at the 90.0 cm mark. • Keeping P at the 90.0 cm mark, he adjusts the position of the metre rule on the pivot so that the metre rule is as near as possible to being balanced. • In Table 1.1, he records the distance a from the 50.0 cm mark to the pivot. (i) Calculate, and record in Table 1.1, the distance b between the centre of load P and the pivot. [1] a (ii) Calculate b. Record its value in Table 1.1. [1] (b) The student repeats the procedure using loads of 1.2 N, 1.0 N, 0.8 N and 0.5 N. The readings and results are shown in Table 1.1. Table 1.1 Weight of a a / cm b / cm load, P / N b 1.5 23.1 1.2 21.2 18.8 1.13 1.0 18.9 21.1 0.900 0.8 16.8 23.2 0.724 0.5 12.5 27.5 0.455 a Plot a graph of weight of load P / N (y-axis) against (x-axis). You do not need to begin your b axes at the origin, (0,0). [4] (c) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ........................................................ [2] (d) The gradient G is numerically equal to the weight W of the metre rule. Write down the value of W to an appropriate number of significant figures for this experiment. Include the unit. W = ........................................................ [2] (e) The student has assumed that the centre of mass of the metre rule is at the 50.0 cm mark. Explain briefly how you would find as accurately as possible the position of the centre of mass of the metre rule. No extra apparatus or materials are available. ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [1] (f) Briefly state the main difficulty that you would have when carrying out this type of balancing experiment. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 12]

Mark scheme: 1(a)(i) b 16.9 1 1(a)(i) a / b 1.37 (ecf allowed) 1 1(b) Graph: Axes correctly labelled and right way round 1 Suitable scales 1 All plots correct to ½ small square 1 Good line judgement, thin, continuous line 1 1(c) triangle method indicated on graph 1 triangle at least half of candidate’s distance between extreme plots 1 1(d) Correct calculation, W = G 1 to 2 or 3 significant figures 1 1(e) Balance on pivot with no load – balance point is at c of m 1 1(f) Obtaining a stable balance 1

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2 A student investigates the resistance of lamps. She uses the circuit shown in Fig. 2.1. power supply A L1 V Fig. 2.1 (a) She records the potential difference V1 across the lamp L1 and the current I1 in the circuit. The meters are shown in Fig. 2.2 and Fig. 2.3. (i) Write down the meter readings. 4 5 6 3 7 0.4 0.6 2 8 0.2 0.8 1 9 0 10 0 1.0 A V Fig. 2.2 Fig. 2.3 V1 = .............................................................. I1 = .............................................................. [3] V1 (ii) Calculate the resistance R1 of the lamp L1 using the equation R1 = . I1 R1 = ........................................................ [1] (b) The student connects a lamp L2 in series with lamp L1. She records the potential difference V2 across lamps L1 and L2 and the current I2 in the circuit. V2 = ..............................................................2.4 V I2 = ..............................................................0.21 A Calculate the combined resistance R2 of lamps L1 and L2 connected in series, using the V2 equation R2 = . I2 R2 = .............................................................. [1] (c) She connects a lamp L3 in series with lamps L1 and L2. She records the potential difference V3 across the three lamps and the current I3 in the circuit. She calculates the combined resistance R3. V3 = ..............................................................2.4 V I3 = ..............................................................0.17 A Ω R3 = ..............................................................14.1 A student suggests that the resistance R3 of the three lamps connected in series should be given by the equation R3 = 3 × R1. State whether the results agree with this suggestion. Justify your answer by reference to the results. statement .................................................................................................................................. justification ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2] (d) Complete the circuit diagram in Fig. 2.4 to show: • the three lamps connected in parallel • the voltmeter connected to measure the potential difference across the lamps • a variable resistor connected to control the current in all three lamps. power supply A Fig. 2.4 [3] [Total: 10]

Mark scheme: 2(a)(i) V = 2.5 1 I = 0.3(0) 1 Both units correct 1 2(a)(ii) R1 8.33 (ecf allowed) 1 2(b) R2 11.4 with unit Ω 1 2(c) Statement matches results 1 Justification matches statement 1 2(d) Lamps in parallel and correct symbol for lamp 1 One voltmeter, with correct symbol, in parallel with lamps 1 Variable resistor in correct position, with correct symbol 1

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3 A student investigates the cooling of water. (a) The thermometer in Fig. 3.1 shows room temperature θR at the beginning of the experiment. Record θR. –10 0 10 20 30 40 50 60 70 80 90 100 110 °C Fig. 3.1 θR = ........................................................ [1] (b) • The student pours 200 cm3 of hot water into a beaker. He places a thermometer in the water. • He measures the temperature θ of the hot water in the beaker. • He immediately starts the stopclock and continues recording the temperature of the water every 60 s. The temperature readings are shown in Table 3.1. Table 3.1 t / θ/ 0 95 89 85 81 78 (i) Complete the time column in Table 3.1. [1] (ii) Complete the column headings in Table 3.1. [1] (c) • Calculate the decrease in temperature Δθ1 during the first 120 s. Δθ1 = .............................................................. • Calculate the decrease in temperature Δθ2 during the last 120 s. Δθ2 = .............................................................. [1] (d) (i) Tick the box to show your conclusion from the results in (c). The average rate of cooling is greater in the first 120 s than the average rate of cooling in the last 120 s. The average rate of cooling is less in the first 120 s than the average rate of cooling in the last 120 s. The average rate of cooling is the same in the first 120 s as the last 120 s. [1] (ii) Justify your conclusion in (d)(i) by reference to the results. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [2] (e) Suggest two ways in which the student could reduce the rate of loss of thermal energy from the beaker in this type of experiment. 1 ............................................................................................................................................... 2 ............................................................................................................................................... [2] (f) Draw a diagram of a measuring cylinder being used to determine the volume of water. Show clearly the water level and draw, with a ruler, a straight line showing the line of sight required to obtain an accurate reading of the volume of water. [2] [Total: 11]

Mark scheme: 3(a) 24 (°C) 1 3(b)(i) Times 60, 120, 180, 240, 300 1 3(b)(ii) Units s and °C 1 3(c) 10, 7 1 3(d)(i) Correct box ticked to match readings 1 3(d)(ii) Justification to match (i), quoting figures 1 Reference to same time 1 3(e) Two from: Insulate Lid Lower starting temperature Higher room temperature Smaller volume of water Smaller surface area 2 3(f) Clearly shown perpendicular line of sight 1 Clearly shown bottom of meniscus 1

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4 A student is investigating the time taken for metal balls to stop moving after being released on a curved track. Fig. 4.1 shows the shape of the track. The track is flexible, so the shape of the curve can be changed. metal ball Fig. 4.1 The following apparatus is available: a selection of metal balls of different masses the flexible track clamps to hold the track a stopwatch a tape measure a metre rule The student can also use other apparatus and materials that are usually available in a school laboratory. Plan an experiment to investigate a factor that affects the time taken for metal balls to stop moving after being released on a curved track. In your plan, you should: • state how you would expect the balls to move • explain how you would carry out the investigation • state which variables you would keep constant and which variable you would change • draw a table, or tables, with column headings, to show how you would display your readings (you are not required to enter any readings in the table) • explain how you would use your readings to reach a conclusion. You may add to the diagram in Fig. 4.1 if it helps your explanation. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... [7] [Total: 7]

Mark scheme: 4 MP1 How the ball will move: Back and forth / like a pendulum 1 MP2 Release from a determined position, time until stops 1 MP3 Repeat with at least two more values of independent variable 1 MP4 Statement of variable to be changed 1 MP5 Statement of a variable to keep constant 1 MP6 Table with columns for chosen variable that is changed and time with correct units, s for time. 1 MP7 Compare chosen variable with time. Or plot graph of chosen variable against time 1

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