Question

# A mass M is suspended as shown in figure. If the system is in equilibrium and K is the spring constant, then the extension produced in the spring is given by (assume pulleys to be massless and strings inextensible.) 4MgKMgK2MgK3MgK

Solution

## The correct option is A 4MgK Let extension in spring be X, From diagram, we get, T1=Mg   .......(1)  T2=T1+T1=2T1   ......(2) KX=T2+T2=2T2   ......(3) Therefore, from (2) and (3) KX=4T1 Now, using (1), we get KX=4Mg ⇒X=4MgK Hence option A is correct

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