To break the sound barrier, you must travel at or faster than the speed of sound in air, which is approximately 767 miles per hour (about 343 meters per second) at sea level and at 68°F (20°C). This speed is also known as Mach 1. The exact speed to break the sound barrier varies with atmospheric conditions such as temperature and altitude because the speed of sound increases with warmer temperatures and decreases with altitude

. For example, at higher altitudes where the air is colder and less dense, the speed of sound is lower, so you need to travel somewhat slower than 767 mph to break the sound barrier there. Conversely, in warmer conditions at sea level, the speed required is closer to 767 mph or slightly higher. Breaking the sound barrier means surpassing this speed threshold, causing shock waves to form around the object and generating a sonic boom. This phenomenon was first achieved by Chuck Yeager in 1947 when he flew the Bell X-1 faster than Mach 1

. In summary:

• Speed to break the sound barrier: approximately 767 mph (343 m/s) at sea level and 68°F
• Varies with altitude and temperature (lower at higher altitudes, higher in warmer air)
• Expressed as Mach 1 (speed of object divided by speed of sound)
• Breaking it produces a sonic boom due to shock waves

Thus, to break the sound barrier, you must travel at least around 767 mph under standard sea-level conditions, with the exact speed depending on environmental factors.