Question

MOMENTS
A uniform rod 8m long weighing 5kg is supported horizontally by 2 vertical parallel strings @ p & Q and @ distances of 2m and 6m from one end.Weights of 1kg,1.5kg and 2kg are attached at distances of 1m, 5m and 7m respectively from the same end.
Find the tension in each vertical sting
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Answer 1

First calculate the total weight of the rod plus the 3 weights. This must be equal to the sum of the tensions in the two supporting strings. That gives you one equation with two unknowns. Then calculate the sum of the moments about some point - whatever seems convenient - and that must be equal to 0. In adding up these moments you can treat the weight of the rod as if it was a point force at its midpoint. Be careful to keep signs for your moments consistent, depending on whether the force is being applied to the left (negative) or right (positive) of the point where you are calculating the moment, and depending on whether the eeofrce is in the up (positive) or down (negative) direction. This gives you a second equation in 2 unknowns. You now have two equations in two unknowns, so you should be able to get your answer. And here's a hint - if for that second equation you calculate the moments about the point where one of the strings is attached, it really simplifies things.