Answer: Hot air is less dense than cool air; the heated air causes the balloon to rise simply because it is lighter than an equal volume of cold air. Buoyancy is an upward force that the air exerts, and it helps hot-air balloons and blimps stay in the air. A hot air balloon uses a burner to heat up the air inside the balloon.
The Roaring Economy of the 1920s. The 1920s have been called the Roaring '20s and for good reason. Not only was American culture 'roaring' in terms of style and social trends, but the economy was 'roaring' as well. The decade was a time of tremendous prosperity.
The answer is George Stephenson. He is credited for the inventing of the steam locomotive called the rocket or "Stephenson's Rocket"
The Devshirme system was a system where Christian boys were recruited by force to serve the Ottoman government.
