# Q.6Are there physical quantities other than temperature that tend to equalize if two different systems are joined?

Qaiser Atta
20 Points
2 years ago

Yes. Fluid pressure is another example. That is why fluid flows from high pressure to low pressure.

Also, mass exchange, via a process called diffusion. Substances that can diffuse will diffuse until concentrations are the same throughout.

Voltage is another physical quantity that will tend to equalize. Suppose you start with a charged capacitor, and connect its leads through a resistor. Over time, the charge will flow off the positive plate and onto the negative plate. This will happen, until the net charge is zero on both capacitor plates. And simultaneously, the voltage difference across the capacitor plates will diminish to zero.

These are very analogous laws in Physics. And it is common that you will see one situation being used as an analogy to explain one of the others. We use a water analogy to explain electric circuits, and we use an electric circuit analogy to explain heat transfer.