Question

An object moving at a speed greater than that of sound is said to be moving at :

• A. infrasonic speed
• B. sonic speed
• C. ultrasonic speed
• D. supersonic speed

Answer 1

The correct option is D supersonic speed

Supersonic speed is a rate of travel of an object that exceeds the Speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 C (68 F) at sea level, this speed is approximately 343.2 m/s, 1,125 ft/s, 768 mph, 667 knots, or 1,235 km/h. Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic. Flight during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic. This occurs typically somewhere between Mach 0.8 and Mach 1.23.