A student performs an experiment to mark the centre of mass C on a thin piece of card. There are two holes in the card. Fig. 2.1 shows the card and two lines that the student draws on the card. [Figure 2.1 (pentagonal card with holes, centre of mass C, and two lines drawn)] key ○ = hole C = centre of mass

1. (a)Describe a method used to draw these two lines in their correct positions on the card. Make clear what extra apparatus is needed. You may draw a diagram, if you wish. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [3][3]
2. (b)(i)The student holds the card loosely between her fingers. The card is vertical, resting with its lower edge on a bench as shown in Fig. 2.2. [Figure 2.2 (card balanced on bench)] The card is tilted slightly, as shown in Fig. 2.3, and then released. [Figure 2.3 (tilted card with anticlockwise and clockwise arrows)] When angle θ is small, the card falls clockwise, back to the position shown in Fig. 2.2. Explain why the card falls anticlockwise when θ is large. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [2][2]
3. (b)(ii)State one change to the card that makes it more stable. ............................................................................................................................................................................. [1][1]

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