What is the Sound?
When something vibrates, it sends waves of energy (vibration) into our ears, which produces sound. The vibrations are carried to the ear by air or another medium (solid, liquid, or gas). The louder the sound, the stronger the vibrations. As you move away from the source, the sounds become fainter. The rate at which an object vibrates to generate sound waves changes the sound.
The speed of the vibrations determines the pitch of a sound (high or low). Different materials produce different pitches; we hear a high-pitched sound when an object vibrates quickly and a low-pitched sound when an object vibrates slowly. Sounds are usually made up of a variety of sound waves.
Sound
Speed of Sound
The speed of sound is the rate at which a wave or vibration passes through a medium or matter. The type of matter significantly impacts the speed at which sound travels. Sound, for example, travels faster in water than in air. In steel, sound travels even faster. The speed of sound in dry air is 343 meters per second (768 mph). At this speed, sound travels one mile in about five seconds. Sound travels four times faster in water (1,482 meters per second) and approximately thirteen times faster in steel (4,512 meters per second).
Sound
Sound Barrier
The speed at which sound travels is referred to as the sound barrier. The speed of a sound wave varies with temperature and air density, increasing by about 0.6 m/s for every degree Celsius increase in temperature. At 68° F, the speed of sound is approximately 343 m/s or 767 mph. When an object approaches the speed of sound (Mach 1), air pressure changes dramatically, and pressure waves form around the object.
This pressure will build up until it reaches Mach 1. It will suddenly decrease at this point, resulting in a sound burst. The speed of Mach 1 at which this burst occurs is commonly referred to as the sound barrier. Aircraft wings had to be redesigned for certain aircraft to fly faster than Mach 1.
Breaking the Sound Barrier Speed
Sonic booms are produced by anything moving faster than sound. An aeroplane, a bullet, or even the point of a bullwhip can cause this effect. Supersonic jets, or aircraft that can fly faster than the speed of sound. The loud boom, known as a sonic boom, can be heard when a plane—or anything—flies faster than the speed of sound (i.e., breaks the sound barrier). This is because of a plane breaking the speed of sound.
The speed at which anything breaks the speed of sound depends on conditions like weather and altitude. Aircraft breaking the sound barrier, the airflow around an aircraft reaches the speed of sound at a speed of about 590 to 620 mph, at which point, according to reports, the control surfaces no longer influence the direction of flight.
Sonic Boom
Solved Questions
1. What is sound?
A sound is a form of energy produced by vibrations. The vibrations travel to the ear via the air or another medium (solid, liquid, or gas). The louder the sound, the stronger the vibrations. As you move away from the source, the sounds become fainter.
2. Can sound travel in space?
For sound to travel, a medium is required. Since no molecules can be squeezed and expanded in space, sound cannot travel through a vacuum. The vocal cords, located inside Adam's apple, vibrate to create our voice. When you generate a sound, its vibration travels through the air and is perceived as sound by your brain when it enters your ears.
3. What is the sound barrier?
Ans: The speed at which sound travels is referred to as the sound barrier. The speed of a sound wave varies with temperature and air density, increasing by about 0.6 m/s for every degree Celsius increase in temperature.
Learning by Doing
Write True or False.
Sound travels in solid, liquid and gases________
Speed of sound is 343m/s__________
Summary
Sound is a form of energy that can be heard and it travels in waves.When matter vibrates or it moves back and forth very quickly, then the sound is heard. Sound waves can travel through solids, liquids and gases. Sound needs a medium to propagate. Thus, it cannot travel in space and travels with a speed of 343m/s in the air. A Sonic Boom happens when an aircraft breaks the sound barrier.
FAQs on Breaking the Speed of Sound
1. What is the 'sound barrier' in the context of physics?
The sound barrier is not a physical wall, but a term that describes the sudden increase in aerodynamic drag and other effects an object experiences as it approaches the speed of sound. As an object accelerates, it creates sound waves that move ahead of it. When the object reaches the speed of sound (also known as Mach 1), it catches up to its own sound waves, compressing them into a single, highly energetic shock wave.
2. What happens when an object breaks the speed of sound?
When an object travels faster than the speed of sound, it creates a massive shock wave. This shock wave travels outwards in a cone shape behind the object. When this cone of pressurised air passes over an observer on the ground, they hear a loud, thunder-like clap known as a sonic boom. The object itself has already passed the observer by the time the sound is heard.
3. At what speed do objects break the sound barrier?
The speed of sound is not constant; it depends on the medium it's travelling through, primarily its temperature and density. In dry air at sea level (20 °C), the speed of sound is approximately:
- 343 metres per second (m/s)
- 1,235 kilometres per hour (km/h)
- 767 miles per hour (mph)
4. How does an aircraft manage to break the sound barrier?
Breaking the sound barrier requires overcoming immense air resistance. Supersonic aircraft are designed with specific features to achieve this:
- Powerful Engines: They need engines that provide enough thrust to exceed the powerful drag near Mach 1.
- Aerodynamic Shape: They often have a sharp nose and thin, swept-back wings to slice through the air more effectively and manage the shock waves.
5. What is the main difference between a sonic boom and the sound from a regular, slower aircraft?
The sound from a regular, subsonic aircraft is continuous because the sound waves travel ahead of it, reaching you before the plane does. A sonic boom is fundamentally different; it's a single, explosive sound created when the built-up shock wave from a supersonic object passes over you. You hear the entire compressed sound energy at once, not as a continuous engine noise.
6. Why does sound travel at different speeds in solids, liquids, and gases?
Sound travels fastest in solids, slower in liquids, and slowest in gases. This is because sound is a mechanical wave that needs a medium to travel. The speed depends on how closely the particles of the medium are packed. In solids, particles are very close and tightly bonded, allowing vibrations to pass from one particle to the next extremely quickly. In gases, particles are far apart and must travel a greater distance to collide and transfer the sound energy, making the process much slower.
7. Why can't sound travel in the vacuum of space?
Sound is a mechanical wave, which means it requires the vibration of particles (like atoms and molecules) to propagate or move. The vacuum of space is almost entirely empty, with very few particles. Without a medium to vibrate, sound waves have nothing to travel through, resulting in complete silence. This is why explosions in space, as shown in movies, would realistically be silent.
8. Why are supersonic flights over populated areas often restricted?
Supersonic flights over populated areas are restricted primarily because of the sonic boom they produce. The sonic boom is extremely loud and can be startling to people and animals. The powerful shock wave can also cause physical damage, such as shattering windows and cracking plaster. Due to this noise pollution and potential for damage, government bodies like the FAA in the United States have banned overland supersonic flight by civil aircraft.
