What is Mach number ?
It is the ratio of the speed of object to the speed of sound in the same medium
What is an acoustic wave ?
It is simply a sound wave
What is the velocity of a sound wave at STP in air ?
Around 333 m/s
What are the frequencies acoustic waves lie in ?
20 to 20,000 Hz
What are ultrasonic waves ?
Pressure waves that have frequencies greater than 20,000 Hz
What is the speed of an ultrasonic wave ?
Same speed as sound
What is a subsonic wave ?
A mechanical waves moving in a fluid with velocity less than that of sound
What is the Mach number so subsonic waves ?
Less than 1
What are some examples of subsonic motion ?
Vehicles such as motor cars and trains, birds
Where does the sound emitted by a body moving with subsonic motion go ?
It goes ahead of the body and moves away
What is a supersonic wave ?
It is a mechanical wave which travels with a speed greater than that of sound
Where does the sound emitted by a body travelling with supersonic speed go ?
The body moves ahead by piercing it's own sound curtain
What kind of wave is formed by supersonic motion ?
A series of expanding sound waves, with their centers continuously displaced along trajectory
What is the amplitude of a supersonic wave ?
It is high, and affects the medium
What is Mach cone, formed at supersonic speed ?
A number of tangents drawn to the expanding sound waves for a Mach cone
What are hypersonic waves ?
Mach number greater than 5 Special case of supersonic waves
What are transonic waves ?
Mach number in between 0.8 and 1.2 Domain in which change of phase from subsonic to supersonic occurs
What is a shock wave ?
It is a surface that manifests as a sudden discontinuity in a fluid medium, in which it is propagating with supersonic speed
What does a shock wave cause ?
Sudden increase in pressure, temperature and density of gas through which it propagates
What is a closed system ?
A system that does not exchange matter with outside and not acted upon by external forces
What is the law of conservation of matter ?
The total mass of any isolated system remains unchanged, regardless of any physical or chemical change within it
What is the law of conservation of momentum ?
In a closed system, total momentum remains constant
What is the law of conservation of energy ?
The total energy of a closed system remains constant and is independent of any changes within the system
What is extra-corporal lithitripsy ?
It is a shock wave therapy for treating kidney stones
What happens in it ?
The kidney stones are shattered into fragments
What happens to the shattered kidney stones ?
Smoothly passed out through urinary tracts
How can shock waves assist in drug delivery ?
It can replace needles
How are drugs delivered using shock waves ?
The drug is kept in a cartridge and pressed to the skin
How does the shock wave enter ?
Directly through the porosity of the skin
What is the normal penetration ?
About 100 microns