If we use a common alkyl halide, such as methyl bromide, and a common solvent, ethanol, we can examine the rate at which various nucleophiles substitute the methyl carbon. Nucleophilicity is thereby related to the relative rate of substitution reactions at the halogen-bearing carbon atom of the reference alkyl halide.
U.S. Navy. For an airplane to break the sound barrier, it must hit speeds of about 770 mph â when it does that a couple of things happen. All the air in front of the craft gets pushed together, can't get out of its own way â and when that magic number gets hit â the air finally breaks free and crashes behind the plane causing a sonic boom.
The actual speed of sound varies depending on the altitude above sea level because sound travels at slightly different speeds at different temperatures and the temperature varies according to altitude. At sea level, the speed of sound is about 761 miles per hour (1,225 kilometers per hour). At 20,000 feet (6,096 meters), the speed of sound is 660 miles per hour (1,062 kilometers per hour). The speed of sound is commonly refered to as Mach 1, named after the 19th century Austrian physicist Ernst Mach [for biographical details click here].