Transcription: Fill a toy balloon with a gas that is lighter than air, such as helium. Release the balloon and it rises. This is because the total weight of the balloon and the gas together are lighter than the air that would occupy the space the balloon takes up. This same principle governs large balloons and airships and is the reason for their classification as lighter than aircraft. Balloons and airships have a long and varied history of both scientific and military use. Today ballooning is a popular sport.
(.mp4)