In 2012, who became the first man to travel faster than the speed of sound without vehicular power when he jumped from a helium balloon at a height of approximately 24 miles?
Felix Baumgartner Felix Baumgartner Felix Baumgartner (; born 20 April 1969) is an Austrian skydiver, daredevil, and BASE jumper. He is best known for jumping to Earth from a helium balloon in the stratosphere on 14 October 2012. Doing so, he set world records for skydiving an estimated , reaching an estimated top speed of , or Mach 1.25. He became the first person to break the sound barrier without vehicular power relative to the surface on his descent. He broke skydiving records for exit altitude, vertical freefall distance without drogue, and vertical speed without drogue. Though he still holds the two
Speed of sound speed of sound of a monatomic gas goes up by a factor of This gives the 9% difference, and would be a typical ratio for speeds of sound at room temperature in helium vs. deuterium, each with a molecular weight of 4. Sound travels faster in helium than deuterium because adiabatic compression heats helium more since the helium molecules can store heat energy from compression only in translation, but not rotation. Thus helium molecules (monatomic molecules) travel faster in a sound wave and transmit sound faster. (Sound travels at about 70% of the mean molecular speed in gases; the figure