A-level PHYSICS Paper 3 Section A Time allowed: The total time for both sections of this paper is 2 hours. You are advised to spend approximately 70 minutes on this section. 2 *02* IB/M/Jun22/7408/3A Do not write

A-level PHYSICS Paper 3 Section A Time allowed: The total time for both sections of this paper is 2 hours. You are advised to spend approximately 70 minutes on this section. 2 *02* IB/M/Jun22/7408/3A Do ...

A-level PHYSICS Paper 3 Section A Time allowed: The total time for both sections of this paper is 2 hours. You are advised to spend approximately 70 minutes on this section. 2 *02* IB/M/Jun22/7408/3A Do not write outside the Section A box Answer all questions in this section. 0 1 Figure 1 shows apparatus used to measure the speed of sound in a steel rod. Figure 1 The steel rod is suspended from a beam using rubber bands. When the hammer is in contact with the end L of the steel rod, a circuit is completed and the signal generator is connected to the oscilloscope. Figure 2 shows the waveform then displayed on the oscilloscope. 3 *03* Turn over ► IB/M/Jun22/7408/3A Do not write outside the Figure 2 box 0 1 . 1 Which control on the oscilloscope should be used to centre the trace vertically on the screen? Tick () one box. [1 mark] X-shift Y-gain Y-shift Question 1 continues on the next page 4 *04* IB/M/Jun22/7408/3A Do not write outside the When the hammer box hits end L, a sound wave travels along the steel rod and is reflected at end R. When the wave returns to L the rod bounces away from the hammer and the circuit is broken. Figure 3 shows the waveform produced by the brief contact between the hammer and L. Note that the waveform has now been centred vertically. Figure 3 Figure 4 shows the time-base setting of the oscilloscope. Figure 4 5 *05* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 1 box . 2 The distance between L and R in Figure 1 is 0.870 m. Deduce the speed of sound in the steel rod. [3 marks] speed of sound = m s−1 0 1 . 3 A student repeats the experiment using a steel rod of twice the length. Explain: • how using the longer rod affects the waveform displayed • any changes needed to get an accurate result for the speed. You should include numerical detail. [4 marks] 8 6 *06* IB/M/Jun22/7408/3A Do not write outside the 0 2 box Figure 5 shows a strip of steel of rectangular cross-section clamped at one end. The strip extends horizontally over the edge of a bench. Figure 5 7 *07* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 2 box . 1 A mass m is suspended from the free end of the strip. This produces a vertical displacement y. A student intends to measure y with the aid of a horizontal pin fixed to the free end of the steel strip. She positions a clamped vertical ruler behind the pin, as shown in Figure 6. Figure 6 Explain a procedure to avoid parallax error when judging the reading indicated by the position of the pin on the ruler. You may add detail to Figure 6 to illustrate your answer. [2 marks] Question 2 continues on the next page 8 *08* IB/M/Jun22/7408/3A Do not write outside the 0 2 box . 2 It can be shown that 3 3 4mgL y Ewt = where: L is the distance between the free end of the unloaded strip and the blocks w is the width of the strip and is approximately 1 cm t is the thickness of the strip and is approximately 1 mm E is the Young modulus of the steel. A student is asked to determine E using the arrangement shown in Figure 5 with the following restrictions: • only one steel strip of approximate length 30 cm is available • m must be made using a 50 g mass hanger and up to four additional 50 g slotted masses • the experimental procedure must involve only one independent variable • a graphical method must be used to get the result for E. Explain what the student must do to determine E. [5 marks] 9 *09* Turn over ► IB/M/Jun22/7408/3A Do not write outside the box Turn over for the next question 7 10 *10* IB/M/Jun22/7408/3A Do not write outside the 0 3 Conductive putty can easily be formed into different shapes to investigate the effect of box shape on electrical resistance. 0 3 . 1 A student uses vernier callipers to measure the diameter d of a uniform cylinder made of the putty. Suggest one problem with using callipers to make this measurement. [1 mark] 0 3 . 2 Table 1 shows the calliper measurements made by a student. Table 1 d1 / mm d2 / mm d3 / mm d4 / mm d5 / mm 34.5 34.2 32.9 33.4 34.0 Show that the percentage uncertainty in d is about 2.4%. Assume that all the data are valid. [2 marks] 11 *11* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 3 box . 3 The length of the cylinder is 71±2 mm. Determine the uncertainty, in mm3 , in the volume of the cylinder. [4 marks] uncertainty = mm3 Question 3 continues on the next