| Let’s suppose that you empty out a 1-litre | | | | floats in a “pool of air” and when you are |
| plastic soda bottle and putt the cap back on it, bind a | | | | standing in an open field you are standing miles deep |
| string around it and with it dive down underneath | | | | at the bottom of “pool of air”. The helium |
| profound end of a swimming pool. If you sit | | | | balloon according to law of buoyancy displaces an |
| underwater maybe 10 feet deep, holding the string, | | | | amount of air and as long as the balloon along with |
| the bottle that is full of air will have a burly craving to | | | | the helium is lighter than air it displaces, the helium |
| mount to the surface. It acts exactly like a helium | | | | balloon will float in air. It spins out that helium is |
| balloon that quickly ascends to the surface of water | | | | extremely lighter than air though the variation is not |
| if you let go off the string .The grounds for this soda | | | | as immense as between water and air but is |
| bottle’s desire to rise to the surface is water | | | | significant enough. Nitrogen weighs around 1.2506 |
| being a fluid,1-liter bottle displaces one liter of the | | | | grams per liter while Helium weighs around 0.1785 |
| fluid. Since the bottle and the air inside weighs less | | | | grams per liter and as nitrogen is major component |
| than the weight of water it displaces, the bottle | | | | of the air we breathe, 1.25 grams is a fine estimate |
| drifts. | | | | for the weight of a liter of air. This elucidates why |
| Same law of buoyancy works for Helium balloons. | | | | airships and helium balloons are usually quite large as |
| In the case of helium balloon that is held by a string | | | | they have to displace a lot of air so as to float. |