If a number of little droplets of water, each of radius `r`, coalesce to form a single drop of radius `R`, show that the rise in temperature will be given by `(3T)/J(1/r-1/R)` where `T` is the surface tension of water and `J` is the mechanical equivalent of heat.

Options

A. `(2T)/(rJ)`
B. `(3T)/(RJ)`
C. `(3T)/(J)((1)/(r )-(1)/( R))`
D. `(2T)/(J)((1)/(r )-(1)/(R ))`

Answer

C

Explanation

Rise in temperature, `triangletheta=(3T)/(JSd)((1)/(R )-(1)/(R ))`
`triangletheta=(3T)/(J)((1)/(r )-(1)/( R))`
`trianglePprop(1)/(t)`