Question

1. why does a hot - air balloon rise? (1 point)

the weight of the balloon is less than the weight of the air displaced by the balloon.
the volume of the air displaced by the balloon is less than the volume of the balloon.
the weight of the air displaced by the balloon is less than the volume of the balloon.

Explanation:

According to Archimedes' principle, an object will rise in a fluid (air is a fluid) if the buoyant force (equal to the weight of the displaced fluid) is greater than the weight of the object. For a hot - air balloon, when the air inside is heated, its density decreases. The weight of the balloon (including the hot air inside) becomes less than the weight of the air it displaces (the buoyant force).

Answer:

The weight of the balloon is less than the weight of the air displaced by the balloon.