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# Moments watch

1. Can someone explain why you use a 2 in this example,
I would have thought that the ratio would have been 5:1 considering thats where the pivot is. I worked the answer out at 833 N
Can you explain why the 2 is used.

cheers the exam is tomorrow
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2. It's 2 because you're working out the moment about the pivot.
The centre of mass is defined as the point through which the force acts, so it is this point you use, 2 metres from the pivot, to work out the anticlockwise moment.

Then becasue the tension is acting 5 metres away from the pivot and must be equal to the weight in order to keep the girder in equilibrium, 2000=5T is correct.

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