1. Gravity: This pulls you downwards towards the center of the Earth. Its strength depends on your mass.

2. Buoyancy: This pushes you upwards, exerted by the fluid (water, air, etc.) you're floating in. Its strength depends on the volume of fluid displaced by your body and the density of the fluid.

Comparing the size of the forces:

* When you are floating, the buoyancy force is equal to the gravitational force. This is why you don't sink or rise; the two forces balance each other out.

* If the buoyancy force is greater than gravity, you will float. This happens when the object is less dense than the fluid.

* If the gravitational force is greater than buoyancy, you will sink. This happens when the object is denser than the fluid.

Example:

Imagine a boat floating on water. The boat's weight (due to gravity) pulls it down. However, the water displaced by the boat exerts an upward buoyancy force. When the boat is floating, these two forces are equal, and the boat stays afloat.

So, in essence, when you float, the forces of gravity and buoyancy are equal in size, creating a state of equilibrium.