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M1 question statics

Well this qs should be fairly easy but i seem to keep getting confuddled.. its q5 from the edexcel 2002 jan m1 paper.

A heavy uniform steel girder AB has length 10 m. A load of weight 150 N is attached
to the girder at A and a load of weight 250 N is attached to the girder at B. The
loaded girder hangs in equilibrium in a horizontal position, held by two vertical steel
cables attached to the girder at the points C and D, where AC = 1 m and DB = 3 m,
as shown in Fig. 1. The girder is modelled as a uniform rod, the loads as particles and
the cables as light inextensible strings. The tension in the cable at D is three times the
tension in the cable at C.

Find
(b) the tension in the cable at C,

(c) the weight of the girder.

Thanks for any help

Reply 1

yazan_l

take the moment about the centre of the girder (as u dont have the weight of the girder...) take moment C.W. = momemt A.C.W.

and u can find the tension...
then for b) take force up = force down... and u can find the weight.