# [Physics] Why do forces/pressures/electrons/temperatures/etc equalize

equilibriumthermodynamics

What causes various forces/etc. like to equalize? I can understand water in a tank being affected by gravity but why do high pressure systems want to move to low pressure systems (vaccuums), electrons move to cover a surface/volume and so on?

This is Newton's 1st and 2nd law. If forces don't balance something will move!

$$\sum F=ma$$

If there is a higher force or pressure in one end, then if it isn't balanced (by equal and opposite forces), the stuff will start moving.

In a water pipe you might have high pressure in one end and low pressure in the other.

In other words this means that a force is pressing from one end, trying to make the water move to the other end - while another but smaller force is pushing from the other end. Like a strong man and a weaker man pushing on each other.

Who will win? Will the water move towards the end of higher or lower pressure?

I guess it is quite obvious that the stronger man will win and the weaker man will be pushed backwards. Meaning that water will be resisted by the lower pressure, so it will slow down a bit, but it will still move towards that end.