Corrected sentence: The warm air inside a hot-air balloon makes it lighter than the air outside, so it floats. When the air inside cools down, it becomes heavier, and the balloon slowly comes down.
Easy step-by-step explanation:
- The balloon has air inside it. A burner warms that air.
- Warm air spreads out and is lighter than the colder air around the balloon.
- Because the air inside is lighter, the whole balloon rises up into the sky.
- To go down, the pilot lets the air cool (by using the burner less or opening a vent).
- When the air inside gets cooler, it becomes heavier, and the balloon slowly comes down.
Simple idea: Warm air = lighter = goes up. Cool air = heavier = goes down. Think of it like a warm bubble floating up in the air.