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 speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium. In dry air at 20 Â°C (68 Â°F), the speed of sound is 343.2 metres per second (1,126 ft/s; 1,236 km/h; 768 mph; 667 kn), or a kilometre in 2.914 s or a mile in 4.689 s. The speed of sound in an ideal gas depends only on its temperature and composition.