Q.

Two springs have their force constant as k1 and k2 (k1>k2). When they are stretched by the same force up to equilibrium:

1 No work is done by this force in case of both the springs  
2 Equal work is done by this force in case of both the springs  
3 More work is done by this force in case of second spring  
4 More work is done by this force in case of first spring  

Ans.

(3)

F1=F2

∵   w1=12k1x12,    k1x1=k2x2=F

w1=12k1[Fk1]2=12F2k1

∴  w2=12F2k2

∵  k1>k2

∴  w1<w2