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# Edexcel M1 Moments (5E) help needed! watch

1. Hello
Im so stuck on this M1 moments question and am on the verge of depression over it.
I usually find moments easy - but this stuff is killing me.
The question is...

A non-uniform rod AB has length 4m and weight 150N. The rod rests in horizontal equlibrium, supported at points C and D, where AC=1m and DB=0.5m. The center of mass of AB is x metres from A. A particle of weight WN is placed on the rod at A. The rod remains in equilibrium and the magnitude of the reaction of C on the rod is 100N

a)Show that 550 + 7W = 300x

The particle is now removed from A and placed on the rod at B. The rod remains in equilibrium and the reaction of C on the rod now has a magnitude 52N.

b) Obtain another equation connecting W and x.
c) Calculate the value of x and the value of W

answers at the back of the book are:
b) W=790 -300x
c) x=2.53 W=30

But how do i answer this question?
Attached Images

2. Add the other information you to your diagram, then take moments around D for part a.
Do the same for part b.
You will have now two simultaneous equations, solve these for part c.
3. Sorry for the quality

4. Thankyou so much!

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Updated: April 16, 2011
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