Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. For cell transport, diffusion is the movement of small molecules across the cell membrane. The difference in the concentrations of the molecules in the two areas is called the concentration gradient . The kinetic energy of the molecules results in random motion, causing diffusion. In simple diffusion, this process proceeds without the aid of a transport protein. it is the random motion of the molecules that causes them to move from an area of high concentration to an area with a lower concentration.
Jeff knows smoking isn't good for you but he still loves the the smell of fresh pipe tobacco. Some of his fondest childhood memories are of sitting on the porch talking to his grandpa as he smoked his pipe. Jeff remembers being fascinated by the smoke as it billowed out of the pipe and wafted across the porch.
Was it kinetic or thermal energy that moved the smoke?