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M1 question

A small box B of weight 400N is held in equilibrium by two light strings AB and BC. the string BC is fixed at C. the end A of string AB is fixed so that AB is at an angle x to the vertical where x < 60 degrees. string BC is at 60 degrees to the vertical. this information is shown in Fig.5.

i) draw a labelled diagram showing all the forces acting on the box

ii) in one situation string AB is fixed so that x = 30 degrees.

by drawing a triangle of forces, or otherwise, calcualte the tension in the string BC and the tension in the string AB

iii) show carefully, but briefly, that the box cannot be in equilibrium if x = 60 degrees and BC remains at 60 degrees to the vertical.

i can do the first question, but cant do the others...help plz

math.JPG10.4KB

Reply 1

mfb3000

I don't have time to do the question now, but looking at the diagram you've drawn, you have BC wrong. Draw BC up and to the right from B, keeping it at 60 degrees from vertical - the 60 degree angle should be from vertically up, not down.