Cambridge IGCSE Physics 0625 — 2018 May/June Paper 6 · Variant 2

1 A student is determining the density of water. She is provided with a plastic cup, shown in Fig. 1.1. Fig. 1.1 (a) She draws around the base of the cup. Her drawing is shown in Fig. 1.2. Fig. 1.2 (i) From Fig. 1.2, take and record measurements to determine an accurate value for the diameter DB of the base of the cup. DB = ................................................... cm [2] (ii) The student places the cup upside down and draws around the rim of the cup. She determines the diameter DT of the rim of the cup. 7.2 cm DT = .............................................................. DB + DT Calculate the average diameter D of the cup using the equation D = . 2 D = ................................................... cm [1] (b) 1. On Fig. 1.3, measure the vertical height h of the cup. h Fig. 1.3 h = ........................................................ cm 2. Calculate the volume V of the cup using the equation V = 0.785 D 2 h. V = ...................................................... cm3 [1] (c) The student fills the cup with water. The mass of the cup with the water is shown in Fig. 1.4. 232 g Fig. 1.4 m Determine the density ρ of water using the equation ρ = and your value from (b)2. V Give your answer to a suitable number of significant figures for this experiment. Include the unit. ρ = ......................................................... [3] (d) Suggest, with a reason, a part of the procedure (a), (b) or (c) that could give an unreliable result for the density of water. part ....................... reason ....................................................................................................................................... ................................................................................................................................................... [1] (e) The student pours the water from the cup into a measuring cylinder. Draw a diagram to show water in a measuring cylinder. Show clearly the meniscus and the line of sight the student should use to obtain an accurate value for the volume of the water. [2] [Total: 10]

Mark scheme: 1(a)(i) 2 or more measurements seen 1 DB = 4.8 ± 0.1 (cm) 1 1(a)(ii) D = 6.0 (cm) 1 1(b) 1 h = 7.8 (cm) AND 2 V = 220(.428) (cm3) 1 1(c) ρ = 1 / 1.1 / 1.05(««.) 1 2 or 3 significant figures 1 g / cm3 1 1(d) any one from: part (a) drawn circle not exact / thickness of rim or cup / thickness of the pencil line part (b) difficult to measure the height (in practice) / D2 increases inaccuracy in D part (c) mass of cup has been ignored 1 1(e) diagram showing clearly: line of sight perpendicular to measuring cylinder 1 to the bottom of the meniscus 1

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2 A student is investigating the cooling of water. Fig. 2.1 shows the apparatus used. thermometer bench Fig. 2.1 (a) The thermometer in Fig. 2.2 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. 2.2 θR = ......................................................... [1] (b) The student pours 200 cm3 of hot water into the beaker. He records the temperature θH of the hot water at time t = 0 and immediately starts a stopclock. He continues recording the temperature readings every 30 s. The readings are shown in Table 2.1. (i) Explain why the student should wait a few seconds after placing the thermometer in the hot water before taking the first temperature reading. ........................................................................................................................................... ...................................................................................................................................... [1] (ii) Complete the column headings in Table 2.1. [1] (iii) Complete the time column in Table 2.1. [1] Table 2.1 t / θ/ 0 70 60 52 49 46 43 (iv) Plot a graph of θ/ °C (y-axis) against t / s (x-axis). You do not need to start the y-axis at the origin (0,0) but the value of room temperature θR must be marked on the y-axis. [4] (c) Draw a horizontal line across the graph grid to indicate the value of room temperature θR, as shown by the thermometer in Fig. 2.2. [1] (d) State two precautions that you would take in order to obtain accurate readings in this experiment. 1. .............................................................................................................................................. ................................................................................................................................................... 2. .............................................................................................................................................. ................................................................................................................................................... [2] (e) A student plans to repeat the experiment using the same thermometer and the same volume of water. Suggest two changes to the apparatus or the procedure that would increase the rate of cooling of the water. 1. .............................................................................................................................................. ................................................................................................................................................... 2. .............................................................................................................................................. ................................................................................................................................................... [2] [Total: 13]

Mark scheme: 2(a) 1 2(b)(i) ensure thermometer / bulb / alcohol / mercury has reached the temperature of the water 1 2(b)(ii) s / seconds, °C 1 2(b)(iii) t values 30, 60, 90, 120, 150 1 2(b)(iv) graph: axes correctly labelled and right way round 1 suitable scales (scales must start below θ R) 1 all plots correct to ½ small square 1 good line judgement, thin, continuous line 1 2(c) horizontal line at θ R correctly positioned 1 2(d) any two from: perpendicular viewing of thermometer stir (before taking temperature reading) don’t let the thermometer (bulb) touch the sides / bottom of beaker wait for thermometer to reach θ MAX before reading 2 2(e) any two from: higher starting temperature / use hotter water use of metal can instead of beaker / metal bench lower room temperature / cold water bath use of a fan container with a greater surface area / larger beaker 2

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3 A student is determining the focal length of a lens. Fig. 3.1 shows the apparatus used. screen illuminated object v lens Fig. 3.1 (a) The student adjusts the position of the screen until a clearly focused image is formed on the screen. (i) On Fig. 3.1, measure the distance v between the centre of the lens and the screen. v = ......................................................... [1] (ii) Fig. 3.1 is drawn 1/5th actual size. Calculate V, the actual distance from the lens to the screen V = ......................................................... [1] (iii) With a clearly focused image formed on the screen, the actual distance from the centre of the lens to the illuminated object, U is 20.0 cm. UV Calculate the focal length f1 of the lens using the equation f1 = . (U + V ) f1 = ......................................................... [2] (b) The student repeats the procedure in (a), using a different distance U. She obtains another value for the focal length f2. 12.2 cm f2 = .............................................................. Calculate the average value fA of the focal length of the lens, using f2 and your value for f1 in (a)(iii). Give your answer to a suitable number of significant figures for this experiment. fA = ......................................................... [2] (c) The student states that taking more measurements improves the reliability of the value obtained for fA. Suggest additional values for U that you would use. ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] (d) State two precautions that you would take in this experiment to obtain accurate readings. 1. ............................................................................................................................................... ................................................................................................................................................... 2. ............................................................................................................................................... ................................................................................................................................................... [2] [Total: 10]

Mark scheme: 3(a)(i) v = 5.8(0) (cm) / 58 (mm) 1 3(a)(ii) V = 29(.0) (cm) 1 3(a)(iii) f1 = 11.8(3673) / 12 (cm) 1 3(b) f A= 12.0 (cm) 1 2 or 3 significant figures 1 3(c) at least 3 new values suggested 1 all new values between 15 cm and 70 cm with at least 5 cm between each value 1 3(d) any two from: use of darkened room / brighter lamp mark position of centre of lens on holder place metre rule on bench / clamp in position ensure object and (centre of) lens are same height (from the bench) object and lens and screen perpendicular to bench move screen slowly / back and forth to obtain best image 2

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4 A student is investigating whether the distance that a toy truck will travel along a horizontal floor, before stopping, depends on its mass. The following apparatus is available to the student: a ramp blocks to support the ramp as shown in Fig. 4.1 toy truck a selection of masses other standard apparatus from the physics laboratory. Plan an experiment to investigate whether the distance that the toy truck will travel along a horizontal floor, before stopping, depends on its mass. In your plan, you should: • explain briefly how you would carry out the investigation • state any apparatus that you would use that is not included in the list above • state the key variables that you would control • 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). You may add to the diagram in Fig. 4.1 to help your description. ramp floor blocks Fig. 4.1 ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...............................................................................................................................................[7] [Total: 7]

Mark scheme: 4 method to include: place truck on ramp (and release) 1 measure distance (travelled) from bottom of ramp 1 repeat with different mass(es) (loaded on the same truck) 1 additional apparatus: (metre) rule(r) / measuring tape 1 control variables: height / angle of ramp / number of supporting bricks 1 release position / height above bench 1 table with clear columns for mass, and distance travelled, with appropriate units in the headings of the table 1 NOTE: The principle to apply here is ‘could I draw a significantly better line, using these points, under examination conditions?’ If the answer is definitely ‘yes’, do not award the mark. NOTE: – If candidate’s scale consists of actual readings at equal intervals this will produce a perfect straight line! The only marks available in this case are the first (axes right way round and labelled) So maximum 1. – If axes are wrong way round, the other 3 marks are still available.

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