The turning effect of a force is measured by its moment. (a) Fig. 8.1 shows a force F acting on an object at point P. The object is free to rotate about an axis at X that is perpendicular to the page. [Figure 8.1] Write down an expression for the moment of F about the axis at X. Draw on Fig. 8.1 to show what is meant by any other term used in your expression.

1. (a)Fig. 8.1 shows a force F acting on an object at point P. The object is free to rotate about an axis at X that is perpendicular to the page. [Figure 8.1] Write down an expression for the moment of F about the axis at X. Draw on Fig. 8.1 to show what is meant by any other term used in your expression.[2]
2. (b)(i)State the principle of moments.[2]
3. (b)(ii)Describe an experiment to verify the principle of moments. Include a diagram to help the description.[3]
4. (c)(i)The cross-sectional area of piston 1 is 0.018m². Piston 1 exerts a force of 4500 N on the oil. Calculate the pressure of the oil due to this force. pressure =[1]
5. (c)(ii)State what is meant by centre of mass.[1]
6. (c)(iii)The centre of mass of the ladder is not halfway along its length. State what this shows about the ladder.[1]
7. (c)(iv)The centre of mass of the ladder is a horizontal distance of 0.90m from the worker's shoulder. Calculate the moment about the worker's shoulder of the weight of the ladder. moment =[2]
8. (c)(v)A bucket of weight 87 N is suspended from the ladder at a horizontal distance of 1.3m from the worker's shoulder. The worker keeps the ladder horizontal by exerting a vertical force at point L. L is a horizontal distance of 0.54 m from his shoulder. Determine the size and direction of the force exerted at L. size of force = direction =[3]

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