That's easy.if the bock goes a distance x then the the change in the total length is 3x.(2x for the string+x for the spring)so the total is 3x.ad there are 2 forces.the spring force +the rod(the one that connects the pulley to block)so the net force is 3T as the tension=force of spring.so the net force on block is 33xk=9kx.and since we displace by x the effective is 9kx/x =9k

In you can think in 2 ways.I)consider the leftmost pulley.I guess its ideal then we can safely consider that the net torque cting on it is zero.which means you are left with fr-Tr=0 implying T=f.or you my thing it as tension will be constant throughout because if we consider the fbd of a small element the net force is zero(as its massless)which means I can extend the same throughout.

hey , sorry please don't bother about options, yes it is asking about some extension,but I think I will be able to solve it myself.But I am not able to understand how is the whole pulley system being replaced by a spring of force constant 9K.

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TopNewestThat's easy.if the bock goes a distance x then the the change in the total length is 3x.(2x for the string+x for the spring)so the total is 3x.ad there are 2 forces.the spring force +the rod(the one that connects the pulley to block)so the net force is 3T as the tension=force of spring.so the net force on block is 3

3xk=9kx.and since we displace by x the effective is 9kx/x =9kLog in to reply

but why should the tension be equal to spring force?

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In you can think in 2 ways.I)consider the leftmost pulley.I guess its ideal then we can safely consider that the net torque cting on it is zero.which means you are left with fr-Tr=0 implying T=f.or you my thing it as tension will be constant throughout because if we consider the fbd of a small element the net force is zero(as its massless)which means I can extend the same throughout.

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hey , sorry please don't bother about options, yes it is asking about some extension,but I think I will be able to solve it myself.But I am not able to understand how is the whole pulley system being replaced by a spring of force constant 9K.

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Hey the first 2 options dimensions looks like they are asking for some extensions etc.why don't you repost it with a complete question

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What to find.I am not able to get the com question

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equivalent spring constant. the answer is given as 9K.

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@Spandan Senapati

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