Question

What is the driving force for \((a)\) heat transfer, \((b)\) electric current flow, \((c)\) fluid flow, and \((d)\) mass transfer?

Short answer

Answer: The driving forces for the mentioned phenomena are: (a) temperature difference, (b) electric potential difference (voltage), (c) pressure difference, and (d) concentration difference.

Step-by-step solution

(a) Driving force for heat transfer

The driving force for heat transfer is the temperature difference between two regions. Heat will always flow from a region of higher temperature to a region of lower temperature, tending to equalize the temperature between the two regions. It occurs through conduction, convection, and radiation.

(b) Driving force for electric current flow

The driving force for electric current flow is the electric potential difference (voltage) between two points in a circuit. The electric current will flow from the region of higher electric potential to the region of lower electric potential, as electrons move to minimize their potential energy. The relationship between voltage, current, and resistance is given by Ohm's law: V=IR, where V is the voltage, I is the current, and R is resistance.

(c) Driving force for fluid flow

The driving force for fluid flow is the pressure difference between two points in a fluid system. Fluid will flow from a region of higher pressure to a region of lower pressure, as pressure is a measure of the fluid's ability to transfer momentum and exert force on its surroundings. This pressure difference can be due to gravity, mechanical force, or thermal expansion, among other factors.

(d) Driving force for mass transfer

The driving force for mass transfer is the concentration difference of a specific species between two regions. Mass transfer will occur from the region of higher concentration to the region of lower concentration to achieve an equilibrium state. This process can take place through processes such as diffusion, osmosis, or more complex transport mechanisms like convection.