Prelim H2P4 MS

1 2021 JC2 Prelim Paper 4 Question 1 MS Q1 Answer Mark Code (b) Measurement of I, V and θ Values of I, V and θ measured to the correct unit within appropriate range. 1 M1 (c) Set up apparatus from a circuit diagram and follow of written instructions  Award 2 marks if the student has successfully collected 6 or more sets of data (I, V and θ), without assistance/intervention.  Award 1 mark if student has successfully collected 5 sets of data ( I, V and θ), without assistance/intervention.  Award zero mark if student has successfully collected 4 or fewer sets of data (I, V and θ), without assistance/intervention.  Deduct 1 mark if student requires some assistance/intervention but has been able to do most of the work independently. Indicate the nature of any assistance.  Deduct 2 marks if student has been unable to collect data without substantial assistance/intervention. Minimum mark for M2 = 0. 2 M2 (c) Layout: Column headings (raw data & calculated quantities: I, V, θ, T, R, ln R, 1/T) Each column heading must contain an appropriate quantity and a unit. Ignore units in the body of the table. There must be some distinguishing mark between the quantity and the unit i.e. solidus is expected. 1 P1 (c) Table of results: raw data (appropriate degree of precision) All values of I, V, θ to the correct precision. 1 P2 (c) Table of results: calculated quantities (appropriate no. of significant figures) For each calculated value of T, R, ln R and 1/T, the number of s.f. should be the same (or one more) as the number of s.f. in the raw data. 1 P3 (c) Table of results: calculated quantities Correctly calculated values of calculated quantities. Allow one slip computation. 1 A1 (d) Linearising Equation Linearising equation and deriving expressions that equate gradient to E/k and y-intercept to ln A. 1 A2 (d) Graph: Layout, choice of scale and labeling of axes Sensible scales must be used. Awkward scales (e.g. 3:10) are not allowed. Scales must be chosen so that the plotted points occupy at least half the graph grid in both x and y directions. Axes must be labelled with the quantity which is being plotted. 1 P4 (d) Graph: plotting of points All observations must be plotted. Check any 3 points and put ticks if correct. Work to an accuracy of half a small square. 1 P5 (d) Graph: trend line and ability to draw best fit line 9749/04/ASRJC/2019MYCT [Turn Over

2 Q1 Answer Mark Code Straight line of best fit – judge by scatter of points about the candidate’s line. There must be a fair scatter of points either side of the line. 1 P6 (d) Interpretation of graph – gradient Gradient – the hypotenuse of the Δ must be greater than half the length of the drawn line. Read-offs must be accurate to half a small square. 1 A3 (d) Interpretation of graph – intercept y-intercept must be read off to the nearest half small square or determined from y = mx + c using a point on the line. 1 A4 (d) Interpretation of graph – values of E and A Values of E and A calculated correctly with units. 1 A5 (e) Identification of anomaly Anomalous data/results, if any, must be identified. Appropriate justification must be given. Otherwise, comment of absence of anomalous data. 1 M3 JC2 Prelim Question 2 MS Q2 Answer Mark Code (b)(ii) Measurement of d Value of d to the nearest mm with correct unit and correct range 1 M1 (b)(iii) Evidence of repeated readings Repeated timings for a value of d, with t>10 s 1 M2 (b)(iii) Calculated quantity T Correct calculation of T to 3 s.f. 1 A1 (c)(i) Calculated quantity k Correct substitution of d, T, l and g to calculate k 1 A2 (c)(i) Calculated quantity k Correct calculation of k value with appropriate s.f. 1 A3 (c)(ii) Determine k by plotting a graph Repeat the experiment with different d by changing the position of the wooden rod to obtain 6 sets of d and T Correct graph plotted 1 A4 (c)(ii) Determine k by plotting a graph Correct method to find k graphically. 1 A5 JC2 Prelim Question 3 MS Q3 Answer Mark Code (a)(i) Measurement of x and h Value of x and h measured to the nearest 1 mm with unit. 1 M1 (a)(ii) Estimating uncertainties Sensible value of x (e.g. 0.2 cm to 0.5cm). Percentage uncertainty in x calculated correctly to 2 s.f. 1 A1

3 Q3 Answer Mark Code (b)(i) Measurement of  and y Value of  measured to the nearest 1 . Value of y measured to the nearest 1 mm with unit. Evidence of repeated readings of  and y. 1 1 M2 M3 (b)(ii) Calculation of tan  Value calculated correctly with appropriate s.f. 1 A2 (c)(ii) Measurement of x, h,  and y Record of readings x, h,  and y.  in (c)(ii) >  in (b)(i). 1 1 M4 M5 (d)(i) Calculation of k values Correct calculation of k values with appropriate s.f. and units. 1 A3 (d)(ii) Validation of relationship Draw conclusion based on stated criterion e.g. not obeyed because % difference in k more than % uncertainty in x. 1 A4 (e)(i) Sources of error 1. Difficult to maintain the position of the tilted cone while measuring angle and height after the ball is dropped, affecting values of  and y. 2. Difficult to measure y accurately with positioning reason (e.g. ruler is not vertical), affecting values of y. 3. Difficult to measure x as the cone changes shape easily, affecting values of x. any 2 1 1 A5 (e)(ii) Improvement 1. Clamp the protractor and ruler with retort stands, and measure angle and height after the ball is dropped. OR Hold the cone using the clamp of the retort stand. Rotate the clamp to drop the ball and tighten the boss after the ball is dropped. Measure angle and height after the ball is dropped 2. Hang a plumbline using a retort stand to check that ruler is vertical. 1 A6 (f)(i) Graph : plotting of points and best-fit line Points correctly plotted. Straight line of best fit – judge by scatter of points about the candidate’s line. There must be a fair scatter of points on either side of the line. 1 P1 (f)(ii) Graph : gradient Gradient – the hypotenuse of the ∆ must be greater than half the length of the drawn line. Read-offs must be accurate to half a small square. Graph : y-intercept y-intercept must be determined from y = mx + c using a point on the line. 1 1 A7 A8 9749/04/ASRJC/2019MYCT [Turn Over

4 Q3 Answer Mark Code (f)(iii) Drawing conclusion Correct conclusion based on whether the y-intercept obtained in (f)(ii) is zero. 1 A9 (g) Planning Diameter of the cone, x, is kept constant Height of the cone, h is varied and corresponding readings for θ taken (where θ is the angle of cone tilted until the ball falls out). Table with correct headings (e.g h / cm, θ / °) Plot a graph of h against θ and draw the best fit curve Accept other suitable graphs e.g.  = khx Read off the value of h which gives  = 60° 1 1 1 1 1 PL1 PL2 PL3 PL4 PL5

5 Prelim P4 Q4 Suggested Solutions and Mark Scheme Diagram Experiment (i) f vs r Dependent variable Independent variables Control variables What? Frequency of rotation, f Distance from centre of turntable to centre of mass, r  mass of cube, m How? Stopwatch Take timing t for N turns. Period, T = t/N f = N/t Vary by adjusting rheostat Half metre rule moving the cube to a different position  electronic balance  use the same cube Experiment (ii) f vs m Dependent variable Independent variables Control variables What? Frequency of rotation, f mass of cube, m  Distance from centre of turntable to centre of mass, r How? Stopwatch Take timing t for N turns. Period, T = t/N f = 1/T Vary by adjusting rheostat electronic balance using cubes of different sizes / mass  Mark on turntable fixed position 9749/04/ASRJC/2019MYCT [Turn Over turntable motor cube r axle of motor through centre of turntable rheostat

6 Procedure 1. How f varies with r, keeping m constant 2. Set up the apparatus as shown. Ensured the motor is securely clamped using a retort stand. 3. Measure and record r using a half metre rule. 4. Measure and record m using an electronic balance. 5. Close the switch to spin the turntab