Two similar springs P and Q have spring constants K P and K Q , such that K P > K Q . They are stretched,…

Two similar springs P and Q have spring constants KP and KQ, such that KP>KQ. They are stretched, first by the same amount (case a), then by the same force (case b). the work done by the springs WP and WQ are related as respectively, in case
  1. WP=WQ;WP>WQ
  2. WP=WQ;WP=WQ
  3. WP>WQ;WQ>WP
  4. WP<WQ;WQ<WP

Solution

KP>KQ
Case (a): Stretched by same amount
WP=12KPx2
WQ=12KQx2 as xP=xQ=x
WP>WQ
Case (b): Stretched by same force,
F=KPxP=KQxQ
xP=FKP;xQ=FKQ
WP=12KPxP2=12KPF2KP2=12F2KP 
WQ=12KQxQ2=12KQF2KQ2=12F2KQ  
WP<WQ

Asked in: NEET 2015 (Phase 1)

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