Have you ever wondered why a balloon rises and floats in the air? Learn about the science behind this phenomenon and the role of helium, temperature, and altitude.
Balloon Rise And Float In the Air is very important question for every science student.A balloon rises in the air for the same reason that a cork rises to the top of water. The upward pressure of the air on the balloon is greater than the weight of the balloon. The resultant upward pressure (and therefore the lifting power of the balloon) is the difference between the weight of the balloon and the weight of its own volume of air.
Balloons are able to rise and float in the air due to the principle of buoyancy. When a balloon is filled with helium or hydrogen gas, it becomes lighter than the surrounding air. This difference in density causes the balloon to float upwards, much like a cork in water.
When a hot air balloon is inflated and on the ground during various festive events, children looking inside the shell often loudly exclaim: “Look, the balloon is empty, there’s nothing in there!”
Indeed, there is nothing visible to the eye inside the shell, but in fact the shell is completely filled with hot air, the elevated temperature of which is maintained by gas burners periodically turned on by the pilot. The air temperature inside the shell can reach 120°C.
Air, like any gas, expands when heated, its volume increases under constant pressure, and its density decreases compared to the density of the air outside the envelope. The colder, denser atmospheric air begins to push the hot air of the envelope upward, and it in turn carries the envelope of the balloon and everything attached to it into the sky – the gondola (basket) with the burner, gas cylinders, pilot and passengers.
The lifting force of the shell increases with the increase of the difference between the air temperature inside the shell and the air temperature outside the shell. According to Archimedes’ law, a body immersed in a liquid or gas experiences a buoyant force equal to the weight of the liquid or gas displaced by the body.
Considering that the mass of the basket with the burner and two gas cylinders is 230 kg, the resulting lifting force of such an aerostat will be: 765 – 230 = 535 kg. It turns out that this aerostat will easily lift five passengers weighing 100 kg each into the sky.
Of course, in reality the lifting force will be less than we calculated due to the uneven distribution of air temperature along the height of the shell, but still the lifting force of such a balloon is quite large.
It should be noted that as the ambient air temperature increases, the lifting force of the balloon decreases, since the envelope cannot be heated above 120°C.
To determine the maximum weight that a balloon can lift at a certain air temperature, the pilot uses special tables. So at a temperature of +35°C, the balloon can fly only with one pilot and no passengers.
In conclusion, the reason why a balloon rises and floats in the air is due to the principle of buoyancy. By filling the balloon with a gas that is lighter than the surrounding air, and controlling the temperature and altitude, we are able to enjoy the spectacle of balloons gracefully floating in the sky. Next time you see a balloon soaring overhead, you will have a deeper understanding of the science behind its flight.