Cambridge IGCSE Physics 0625 — 2023 Feb/March Paper 5 · Variant 2

1 In this experiment, you will determine the diameter of a marble by two methods and calculate the density of the material from which the marble is made. Method 1 Carry out the following instructions, referring to Fig. 1.1. D marbles scale wooden block metre ruler Fig. 1.1 (Apparatus viewed from above) (a) (i) Place the metre ruler on the bench with its scale facing upwards. Arrange one of the wooden blocks and the five marbles as shown in Fig. 1.1. Measure the length D for the five marbles. D = .......................................................... cm Using your value of D, calculate the average diameter d1 of one marble. d1 = .......................................................... cm [2] (ii) Suggest why it is more accurate, when using a ruler, to measure D for five marbles rather than measure the diameter of a single marble. ........................................................................................................................................... ........................................................................................................................................... ..................................................................................................................................... [1] Method 2 (b) Describe how the two wooden blocks and one of the marbles can be used to determine an accurate value for the diameter of a marble. Draw a diagram to show your suggested arrangement. Describe clearly how you ensure that your value for the diameter of a marble is as accurate as possible. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Use your arrangement to measure the diameter d2 of the marble. d2 = .......................................................... cm [2] (c) (i) Use the top-pan balance as shown in Fig. 1.2 to measure the mass m of one of the marbles. marble top-pan balance bench Fig. 1.2 m = ....................................................... g [1] (ii) Pour approximately 25 cm3 of water into the measuring cylinder. Record the reading V1 of the water level in the measuring cylinder. V1 = ........................................................ cm3 Carefully place the 5 marbles into the water in the measuring cylinder as shown in Fig. 1.3. water measuring cylinder marbles bench Fig. 1.3 Record the new reading V2 of the water level in the measuring cylinder. V2 = ........................................................ cm3 Calculate a value for the average volume V of one marble. Use the equation V2 – V1 V = . 5 V = ........................................................ cm3 [1] (iii) Draw, on Fig. 1.3, an arrow showing the correct line of sight for reading the water level in the measuring cylinder. [1] (iv) Calculate a value for the density ρ of the material from which the marble is made. Use your values of m from (c)(i), V from (c)(ii) and the equation m ρ = . V ρ = .............................................. g / cm3 [1] (d) Describe one possible source of inaccuracy in the method described in (c) and suggest one improvement to reduce its effect. source of inaccuracy ................................................................................................................. ................................................................................................................................................... improvement ............................................................................................................................. ................................................................................................................................................... [2] [Total: 11]

Mark scheme: Question Answer Marks 1(a)(i) sensible value for D (5.0–10.0 cm) and recorded to 1 or 2 d.p. 1 d1 = D / 5 1 1(a)(ii) effect of uncertainties reduced / diameters of marbles may vary 1 1(b) use marble between two blocks and measure gap 1 d1 recorded and suitable means of ensuring accuracy e.g.: 1 measure gap in at least two places and check equal to ensure blocks are parallel / rotate marble to different axis and take average of measurements 1(c)(i) sensible value for m and recorded to at least 1 decimal place 1 1(c)(ii) V2 > V1 and V calculated correctly 1 1(c)(iii) perpendicular arrow / line indicating lower meniscus 1 1(c)(iv) in sensible range recorded to 2 / 3 sig figs 1 1(d) suitable source of inaccuracy e.g.: 1 graduations on measuring cylinder too large / marbles may have different masses improvement matching source of inaccuracy e.g.: 1 use smaller measuring cylinder or greater number of marbles / measure 5 and take average mass

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2 In this experiment, you will investigate the cooling of hot water from different initial temperatures. Carry out the following instructions, referring to Fig. 2.1. clamp thermometer boss beaker stand bench Fig. 2.1 (a) Experiment A Pour 100 cm3 of hot water into the beaker. Place the thermometer in the water in the beaker. In the first row of Table 2.1, record the temperature θA of the water at time t = 0 s and immediately start the stop-watch. Record, in Table 2.1, the temperature θA of the water at times t = 30 s, t = 60 s, t = 90 s, t = 120 s, t = 150 s and t = 180 s. [1] Empty the beaker. (b) Experiment B Pour 100 cm3 of hot water into the beaker. Place the thermometer in the water in the beaker. Wait until the temperature θB of the water has reached the same value as the temperature θA at t = 90 s in Experiment A. In the first row of Table 2.1, record this temperature θB of the water at time t = 0 s and immediately start the stop-watch. Record, in Table 2.1, the temperature θB of the water at times t = 30 s, t = 60 s, t = 90 s, t = 120 s, t = 150 s and t = 180 s. Table 2.1 t / s θA / °C θB / °C 0 30 60 90 120 150 180 [3] (c) Write a conclusion stating how the temperature at t = 0 s affects the rate of cooling of the water. Justify your answer by reference to values from your results. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (d) (i) Calculate the average cooling rate x1 during the second half of Experiment A. Use your readings from Table 2.1 and the equation θA90 – θA180 x1 = T where T = 90 s and θA90 and θA180 are the temperatures at t = 90 s and t = 180 s in Experiment A. Include the unit for the cooling rate. x1 = ......................................................... [2] (ii) Calculate the average cooling rate x2 during the first half of Experiment B. Use the readings from Table 2.1 and the equation θB0 – θB90 x2 = T where T = 90 s and θB0 and θB90 are the temperatures at t = 0 s and t = 90 s in Experiment B. x2 = ......................................................... [1] (iii) A student suggests that x1 and x2 should be the same. State whether your results support this suggestion. Justify your statement by reference to your results. statement .......................................................................................................................... justification ........................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... [1] (e) State one variable which must be controlled so that the comparison of x1 and x2 is valid. ................................................................................................................................................... ............................................................................................................................................. [1] [Total: 11]

Mark scheme: 2(a) A decreasing and recorded to at least 1 °C 1 2(b) B decreasing 1 more slowly than A 1 initial B same as A at 90 s 1 2(c) statement matching readings in table 1 comparison of temperature changes over 180 s, matching statement 1 2(d)(i) correct calculation of x1 1 unit °C / s 1 2(d)(ii) x2 within10% of x1 1 2(d)(iii) statement matching results 1 and justification referencing ‘limits of experimental accuracy’ 2(e) suitable control e.g.: 1 same volume of water, same material of beaker, same thickness of beaker, same surface area (of beaker), same shape of beaker same room temp / named appropriate environmental condition

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3 In this experiment, you will determine the resistance per unit length of a resistance wire. The circuit has been set up for you. Carry out the following instructions, referring to Fig. 3.1. V A crocodile clip 0 cm metre ruler l resistance wire Fig. 3.1 (a) Connect the crocodile clip to a length l = 20.0 cm of the resistance wire. Close the switch. Measure and record in Table 3.1, the value of potential difference (p.d.) V and current I for the resistance wire. Connect the crocodile clip to lengths l = 40.0 cm, l = 60.0 cm, l = 80.0 cm and l = 100.0 cm of the resistance wire. For each length l, measure and record in Table 3.1, the value of potential difference V and current I for the resistance wire. Open the switch. Table 3.1 l / cm V / V I / A R / Ω 20.0 40.0 60.0 80.0 100.0 [2] (b) For each length l calculate and record in Table 3.1, the resistance R of the resistance wire. Use your values of V and I from Table 3.1 and the equation V R = . I [2] (c) Plot a graph of R / Ω (y-axis) against l / cm (x-axis). Draw a straight line of best fit. [4] (d) (i) Determine the gradient G of the graph. Show clearly on the graph how you obtained the necessary information. G = ......................................................... [1] (ii) The gradient G is numerically equal to the resistance per unit length R0 of the resistance wire. Write down the value of R0 for the resistance wire. R0 = ............................................... Ω / cm [1] (e) Suggest one practical reason why students carrying out this experiment may not obtain the same readings as yours. Assume that the procedure has been done carefully. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [1] [Total: 11]

Mark scheme: 3(a) 5 sets of V < 4 V and I <1 A 1 V all increasing 1 and I all decreasing 3(b) correct calculations of R 1 to consistent 2 or consistent 3 significant figures 1 3(c) graph: • axes labelled with quantity and unit 1 • appropriate scales (plots occupying at least ½ grid) 1 • plots all correct to ½ small square and precise plots 1 • well judged line and thin line 1 3(d)(i) G present and triangle method seen on graph 1 3(d)(ii) R0 in range 0.05 to 0.11( / cm) 1 3(e) any one inherent source of inaccuracy e.g.: 1 difficult to position crocodile clip accurately/ inconsistent connection with crocodile clip/ resistance wire not uniform

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4 A student investigates the motion of a ball through the air. Plan an experiment which will enable him to investigate how the range of the ball depends on the angle at which it is launched. The range is the horizontal distance that the ball travels after leaving the end of the channel shown in Fig. 4.1 and before hitting the ground. You are not required to do the experiment. The apparatus available includes: • a flexible channel, as shown in Fig. 4.1, which can be bent at different angles • a selection of balls, each of different diameter and mass. In your plan, you should: • list any additional apparatus needed • explain briefly how to do the experiment – you may add to Fig. 4.1 if it helps your explanation • state the key variables to keep constant • draw a table with column headings, to show how to display the readings (you are not required to enter any readings in the table) • explain how to use the results to reach a conclusion. flexible channel variable angle floor Fig. 4.1 .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. .................................................................................................................................................................. ............................................................................................................................................................ [7]

Mark scheme: 4 MP1 apparatus: 1 metre ruler, protractor MP2 method: 1 set initial launch angle roll ball measure range MP3 repeat for different angle 1 MP4 control variable (one from): 1 diameter of ball, mass of ball. angle / height of (upper end of) channel MP5 table: 1 with columns for independent variable and dependent variable (at least) and both with units MP6 analysis: 1 compare readings in a table to see if change in independent variable produces change in dependent variable, plot (line) graph (with axes specified) MP7 additional point (one from): 1 at least 5 sets of data taken, repeat each measurement and take average, means of accurate indication of point at which ball hits floor, clear indication of where to measure range from

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