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.

Explanation

To solve the problem, we need to derive the expression for the rise in temperature when several small droplets of water coalesce into a larger drop. We will follow these steps:

### Step 1: Understand the concept of work done due to surface tension
When droplets coalesce, the surface area changes, and work is done against the surface tension. The work done (W) is given by:
\[ W = T \cdot \Delta A \]
where \( T \) is the surface tension and \( \Delta A \) is the change in surface area.

### Step 2: Calculate the initial and final surface areas
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