State the principle of moments.

1. (a)State the principle of moments.[2]
2. (b)(i)An airline passenger wishes to check the weight of a suitcase that he carries as hand luggage onto an aeroplane. He uses a uniform plank of wood, pivoted at its centre, as shown in Fig. 2.1. [Figure 2.1] The plank is balanced with the suitcase on one side of the pivot and three bags of sugar, each of mass 2.0 kg, on the other side. The distances are shown in Fig. 2.1. Calculate the weight of one bag of sugar. weight = .................................................... N[1]
3. (b)(ii)The maximum weight of a suitcase that can be carried onto the aeroplane is 67 N. Determine whether the weight of the suitcase exceeds the maximum allowed. Show a calculation in your answer.[2]
4. (c)(i)A tall bus is tested for stability. Fig. 2.2 shows the bus on a slope. [Figure 2.2] The centre of gravity of the bus is marked. State what is meant by the 'centre of gravity' of an object.[1]
5. (c)(ii)When the slope is made very steep, the bus falls over by rotating about point P. Explain why the bus falls over.[2]

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