Physics 2025 · Oct/Nov

Fig. 1.1 shows a model wind turbine with blades, each of length L, placed in moving air . blade terminals bench turbine moving air The area of the circle swept by the blades of the turbine is A. The output of the turbine has two terminals. The turbine is connected to a resistor of resistance R. At a speed v of the moving air , the current in the resistor is I. The atmospheric pressure is P and the thermodynamic temperature of the air is T. It is suggested that I is related to v by the relationshipAPv where Q is a constant. Plan a laboratory experiment to test the relationship between I and v. Draw a diagram showing the arrangement of your equipment. Explain how the results could be used to determine a value for Q. In your plan you should include: 9TTTTuTTTTTTTi9 Diagram 9TTTTuTTTTTTTs9 9TTTTuTTTTTTT 9

A student observes the orbits of some of the moons around the planet Saturn, as shown in Fig. 2.1. Rhea Dione Tethys Enceladus Saturn Mimas Pandora Fig. 2.1 (not to scale) For the moon Pandora, the period of the orbit and the mean distance from the centre of Saturn are determined. The measurements of period T and mean distance r are repeated for other moons. It is suggested that T and r are related by the equationT =2πr where n and k are constants. gradient = [1] * 0000800000005 * 9TTTTuTTTTTTTd9

Values of r and T are given for dif ferent moons in Table 2.1. Table 2.1 moon r / 10 m T / 10 s lg (r / 10 m) lg (T / 10 Pandora 1.42 52 ± 5 Mimas 1.86 81 ± 5 Enceladus 2.38 120 ± 10 Tethys 2.95 170 ± 10 Dione 3.77 240 ± 20 Rhea 5.28 390 ± 30 Calculate and record values of lg (r / 10 m) and lg (T / 10 s) in Table 2.1. Include the absolute uncertainties in lg (T / 10 s).

(i) Plot a graph of lg (T / 10 s) against lg (r / 10 m). Include error bars for lg (T / 10 s).

Draw the straight line of best fit and a worst acceptable straight line on your graph. Label both lines.

Determine the gradient of the line of best fit. Include the absolute uncertainty in your answer. gradient = [2] * 0000800000006 * 9TTTTuTTTTTTTo9 lg (T / 10 lg (r / 10 0.1 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 0.2 0.3 0.4 0.5 0.6 0.7 0.8 * 0000800000007 * 9TTTTuTTTTTTTc9 answer.

Using your answers to

, determine the values of n and k. Include the absolute uncertainties in n and k. Y ou need not be concerned with units. n = k =

Titan is another moon of Saturn. The orbit of Titan has a period of 1.38 × 10 Determine the value of r for Titan. r = m [1] [Total: 15] Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. * 0000800000008 * 9TTTTuTTTTTTTu9