When does equilibrium occur?

Equilibrium occurs when all the forces acting on an object are balanced. The sum of the +x forces on an object equals the sum of the –x forces and the net force on the object is zero.

There are different types of equilibrium, which correlate with different fields of study. One is thermal equilibrium. Thermal refers to heat and this equilibrium is how much heat is entering or exiting something. Another is hydrostatic equilibrium. Hydro refers to liquids and this equilibrium is related to liquids.

The answer to this question is E. All of the above. Equilibrium is a state where the reactants and products are equal. An example is when two persons pull a rope end by end, both apply the same force, none will get pulled down. It is also present when a moving car came to a full stop when an equal power of the brake to the speed of the car is applied.

Equilibrium is also present to a hanging bulb, the cord acts as the reactant and the bulb is the product. That is why the bulb does not fall off not unless the cord is too thin to carry the bulb or the bulb is too heavy for the cord.