Thursday, 1 December 2011


A light string ABCDE whose extremity A is fixed, has weights W1 & W2 attached to it at B & C. It passes round a small smooth pulley at D carrying a weight of 300 N at the free end E as shown in figure. If in the equilibrium position, BC is horizontal and AB & CD make 150° and 120° with BC, find (i) Tensions in the strings and (ii) magnitudes of W1 & W2

Although ABCDE is a single string/rope but still the tensions in the string/rope will be different at different segments like in the segment AB the tensions will be T1 , but in BC segment it will be different as the weight is attached at a fixed point (point B) on the string, hence it will be T2 here and in CD it will be T3  there. As at point D the string is not attached rather passes over a smooth pulley hence the tension in DE and CD will be same ie. T3  again.

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