Question

A supersonic plane flies with a speed:

• A. Of sound
• B. Less than the speed of sound
• C. Greater than the speed of sound
• D. Of light

Hint:

Break the word supersonic into its parts, super meaning beyond, sonic meaning sound.

Answer 1

The Correct Option is C

Step 1: The prefix "super" means beyond or above, and "sonic" refers to sound. So the word supersonic literally means beyond the speed of sound.

Step 2: The speed of sound in air at normal conditions is close to 340 metres per second, roughly 1235 kilometres per hour, and this speed is often called Mach 1.

Step 3: A plane flying slower than this speed is called subsonic, one flying at exactly this speed is transonic, and a supersonic plane is defined as one that cruises faster than Mach 1, that is, faster than the local speed of sound.

Step 4: Such planes produce a shock wave called a sonic boom when they cross the sound barrier, because they are moving faster than the pressure disturbances they create can move away from them.

Step 5: So a supersonic plane flies at a speed greater than the speed of sound, which is option C.