CONCEPT:
- Supersonic speed: An object moving with a speed greater than the speed of sound is said to move with a supersonic speed.
- Generally, a bullet fired from a gun and aircraft moves with supersonic speed.
- The speed of sound is about 768 miles per hour (1,236 kilometers per hour) at sea level.
- Supersonic speeds are described by their "Mach number".
- Mach number: The ratio of the speed of the object to the speed of sound in the air of the same temperature and density is called Mach number.
- Supersonic includes speeds up to five times faster than the speed of sound, or Mach 5.
EXPLANATION:
- When the speed of any object exceeds the speed of sound, it is said to be traveling at Supersonic speed. So option 2 is correct.
EXTRA POINTS:
- Subsonic has a speed of less than 0.8 Mach.
- Hypersonic may have a speed between 5-10 Mach.






