1. Buoyancy: This is the upward force exerted by the surrounding air on the balloon. Hot air is less dense than cool air, so the balloon filled with hot air is lighter than the same volume of air around it. This difference in density creates an upward force that lifts the balloon.
2. Gravity: This is the downward force exerted on the balloon by the Earth's gravity. It acts on the mass of the balloon, the basket, and everything inside.
These two forces are constantly working against each other. When the buoyancy force is greater than the force of gravity, the balloon rises. When the forces are equal, the balloon hovers. And when gravity is stronger, the balloon descends.
