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Eight mercury drops, each of radius r, coalesce to form a bigger drop. The surface energy released in this process is . (S is the surface tension of mercury).
(2) 16 r2S
Volume is conserved: 43 R3=8 43 r3 R=2r
Initial area =8 4 r2=32 r2
Final area =4 (2r)2=16 r2
Decrease in area A=32 r2-16 r2=16 r2
Energy released =S A=16 r2S
Answer: (2)
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