"What goes up must come down" is a saying that refers to the law of physics that states that anything that goes up will eventually come back down. This law is constantly in effect, no matter what people or objects are doing. The reason why this law works in the law of physics is because of gravity. Gravity is a force that attracts objects towards each other. The more mass an object has, the more gravity it has. This is why the Earth has more gravity than a moon, for example. Gravity pulls objects towards each other, which is why when something goes up, it must come down.

The saying "what goes up must come down" is sometimes used metaphorically to describe, among other things, power and success. However, the origin of the saying is not clear. Some sources place it in the 1870s, while others attribute it to Isaac Newtons third law of motion. Newtons third law of motion states that for every action, there is an equal and opposite reaction.

Several factors contribute to how quickly an object comes down once it goes up. One factor is the speed at which the object is moving. The faster an object is moving, the quicker it will come down. Another factor is the height of the object. The higher an object is, the longer it will take for it to come down. Finally, the density of the object also plays a role. The denser an object is, the quicker it will come down.