A large number of water drops, each of radius r, combine to have a drop of radius R. If the surface tension is σ and the mechanical equivalent of heat is J, the rise in heat energy per unit volume will be:
A) (σ/J)(2πr/R)
B) (σ/J)(4πr/R)
C) (σ/J)(πr/R)
D) (σ/J)(8πr/R)