Because when air heats up it expands.
When you blow air into a balloon, you are increasing the pressure inside the balloon. This increase in pressure causes the rubber of the balloon to stretch and expand, filling up with the air you are blowing in. The elastic nature of the rubber allows the balloon to expand and hold the air inside it.
When air is heated, its volume increases. If you fill a balloon with comparably cold air and then let it touch hotter air, the air inside will expand and thereby increase the pressure on the balloon membrane. If this pressure gets too strong, the balloon might pop.
Air is transferred from your lungs into the balloon, where it diffuses inside the balloon and due to the elastic tendancies causes it to expand from the pressure of the increasing amount of air you blow in.
Heating the air inside the balloon causes the air molecules to move faster and spread out, increasing the pressure inside the balloon. This increase in pressure pushes against the balloon's walls, causing it to expand and inflate.
Blowing air into the balloon increases the pressure inside the balloon. This increased pressure pushes against the walls of the balloon, causing it to expand and stretch. The volume of the balloon increases, allowing it to hold more air.
A balloon expands when air is blown into it, causing the rubber or latex material of the balloon to stretch and increase in volume. As more air is added, the pressure inside the balloon increases, causing it to expand and become larger in size.
Heating causes the air inside the balloon to expand. Some of the warm air leaves through the bottom opening of the balloon, keeping the pressure constant.
When a balloon is placed in hot water, the air molecules inside the balloon gain kinetic energy and move faster, causing them to exert more pressure on the walls of the balloon. This increased pressure results in the balloon expanding in order to accommodate the higher volume of air it contains.
When air is blown into a balloon, it fills the space inside. The pressure of the air increases, causing the balloon to expand. If the balloon is sealed, the air inside remains trapped, making the balloon float or hover depending on the amount of air inside.
Heating causes the air inside the balloon to expand. Some of the warm air leaves through the bottom opening of the balloon, keeping the pressure constant.
As the weather balloon rises in altitude, the air pressure around it decreases while the pressure inside the balloon remains relatively constant. This pressure difference causes the gas inside the balloon to expand, increasing its volume and size.
Heat causes the air molecules inside a balloon to move faster and spread out, increasing the pressure inside the balloon. This increased pressure makes the balloon expand and inflate. If the heat is high enough, it can cause the balloon to burst.