AQA-7408-3BC-PHYSICS FINAL MARK SCHEME PAPER 3BC-SECTION B:Engineering physics-A LEVEL-Jun24-v1.0

AQA-7408-3BC-PHYSICS FINAL MARK SCHEME PAPER 3BC-SECTION B:Engineering physics-A LEVEL-Jun24-v1.0. Question Answers Additional comments/Guidance Mark AO 01.2 The mark scheme gives some guidance as to what statements are expected to be seen in a 1- or 2-mark (L1), 3- or 4-mark (L2) and 5- or 6-mark (L3) answer. Guidance provided in section 3.10 of the ‘Mark Scheme Instructions’ document should be used to assist marking this question. Mark Criteria 6 All three areas covered with at least two aspects covered in some detail. 6 marks can be awarded even if there is an error and/or parts of one aspect missing. 5 A fair attempt to analyse all three areas. If there are several errors or missing parts then 5 marks should be awarded. 4 Two areas successfully discussed, or one discussed and two others covered partially. Whilst there will be gaps, there should only be an occasional error. 3 One area discussed and one discussed partially, or all three covered partially. There are likely to be several errors and omissions in the discussion. 2 Only one area discussed, or makes a partial attempt at two areas. 1 One of the three areas covered without significant error. 0 No relevant analysis. Measuring angular speeds (ω1 and ω2) (Both required for full) 1A.Use of optical or magnetic sensor 2A. with datalogger/data-recorder/ more detail 1B. use of video /mobile phone/stroboscope 2B. with more detail 1C. stopwatch and fiducial mark 2C. and finding time for several revs Other measurements (Both required for full) 3. Mass of dropped mass AND Distance of (centre of) mass to centre of turntable/axis of rotation 4A. using top pan balance/scales 4B. using vernier callipers or ruler Calculation (Three points for full; one/two for partial) 5. idea that rev s −1 must be converted to rad s−1 6A. M of I of mass = mr2 (= Imass) 7A. (Imass + I) ω2 = I ω1 6A & 7A. I = mr2ω2 (ω1 - ω2) OR substitute ω1 ω2 m and r into above equations to find I A graphical method might be described, eg 6B. Plot ω1 ω2 against r 2 for various r 7B. I = m gradient 6 AO1 ×1 AO2 ×3 AO3 ×2 Total 9 000007 Page 7 of 15 PHYSICS MARK SCHEME – A-LEVEL PHYSICS – 7408/3BC – JUNE 2024 8 Question Answers Additional comments/Guidance Mark AO 02.1 Use of total area under graph = 2.52 rad  Valid attempt at calculating the area in Figure 4 ωmax = 0.87(1) rad s–1  MP2 eg: 2.52 = [½ (1.5 × 0.35)] + [½ (ωmax + 0.35) × 1.2] + [½ × 3.5 × ωmax] Must show calculation answer to 2 sf or more. 3 AO2 ×3 000008 Page 8 of 15 PHYSICS MARK SCHEME – A-LEVEL PHYSICS – 7408/3BC – JUNE 2024 9 Question Answers Additional comments/Guidance Mark AO 02.2 Idea that T = Iα must be used at times where there is a peak of the Figure 5 graph.  Calculates one value of Iα at the time during any of the 3 accelerations where I is at a peak  Calculates the maximum values of torque for all three acceleration and shows overall maximum value is at t = 2.1 s  MP1: must show that they have considered using peak at 2.1 s and at least one other peak 1st acctn: Tmax = 12200 × 0.35/1.5 = 2850 N m (at 0.65 s) 2nd acctn: Tmax = 10400 × (0.87 – 0.35)/1.2 = 4510 Nm at 2.1 s 3rd acctn: Tmax = 12800 × –0.87/3.5 = –3180 N m (at 5.1 s) Allow ± 200 kg m2 on I Allow use of ωmax = 0.9 rad s–1 giving 2nd acctn Tmax = 4760 N m 3rd acctn Tmax = 3320 N m