When a drop of food coloring enters the water, several processes occur:
1. Diffusion: This is the main process. Molecules of food coloring move from an area of higher concentration (the drop) to an area of lower concentration (the water). They spread out to evenly distribute themselves throughout the water.
2. Advection: If the water is moving (for example, if you stir it), this can carry the food coloring along with it.
3. Convection: If there are temperature differences within the water, these can create currents that move the food coloring around.
Eventually, assuming no other forces are acting on the water (like stirring), the food coloring will evenly distribute itself throughout the water due to the process of diffusion. This is a passive process that doesn't require any energy, as it's powered by the random motion of the molecules.