Apr 17, 2003 · The history of the harp goes back thousands of years. The harp is regarded as the world’s oldest string instrument. It influenced the evolution of the piano, guitar, and violin. Engineering is the application of science to the art of problem solving; the harp has encompassed the ideals of engineering. Through many centuries, harp makers have ...
Place the middle of the string behind your head, pull the string across your ears, and hold the two free ends together in front of your face. The string should cross over the opening in each ear. Pluck the string, and listen to the tone it makes. You can hear your string, but the sounds are so quiet you will not disturb other people even if ...
As soon as the vacuum is achieved in the bell jar, no more sound will be audible from the bell jar. However, in the bell jar, the hammer continues to hit the gong. This means that still the sound is being produced but now we cannot hear it. This is because sound waves always need a medium to propagate. In the bell jar, it was, hence sound waves ...
Mar 20, 2009 · There is one crucially important difference between waves bumping over the sea and the sound waves that reach our ears. Sea waves travel as up-and-down vibrations: the water moves up and down (without really moving anywhere) as the energy in the wave travels forward. Waves like this are called transverse waves.
Place the middle of the string behind your head, pull the string across your ears, and hold the two free ends together in front of your face. The string should cross over the opening in each ear. Pluck the string, and listen to the tone it makes.
Many city bus services do not allow people to play loud music on buses. We find that if you wrap a string around your head and play music, not only will you abide by city laws, but you’ll find yourself with more room as others move away from you.
Sound needs a material medium for their propagation like solid, liquid or gas to travel because the molecules of solid, liquid and gases carry sound waves from one point to another. Sound cannot progress through the vacuum because the vacuum has no molecules which can vibrate and carry the sound waves.
Bell jar is a laboratory equipment used for creating a vacuum. Its shape is similar to that of a bell. Place an electric bell in the bell jar. Start pumping out the air of the sealed bell jar. As we start pumping out the air, the sound of an electric bell coming out of the bell jar starts fading.
A sound is a form of energy produced by the vibration of particles in a medium. Let us understand how sound waves are produced with the help of an example: In a drum, when drum sticks hit the drum, the outer membrane of the drum vibrates up and down.
The first person to discover that sound needs a medium was a brilliant English scientist known as Robert Boyle (1627–1691). He carried out a classic experiment that you've probably done yourself in school: he set an alarm clock ringing, placed it inside a large glass jar, and while the clock was still ringing, sucked all the air out with a pump. As the air gradually disappeared, the sound died out because there was nothing left in the jar for it to travel through.
All these waves add together to give a unique shape to the sound wave produced by different instruments, and that's one reason why they sound different.
That's largely why mighty creatures of the deep rely on sound for communication and navigation. Whales, famously, "talk" to one another across entire ocean basins, while dolphins use sound, like bats, for echolocation. Photo by Bill Thompson courtesy of US Fish and Wildlife Service.
Sound is the energy things produce when they vibrate (move back and forth quickly). If you bang a drum, you make the tight skin vibrate at very high speed (it's so fast that you can't usually see it), forcing the air all around it to vibrate as well.
Sound waves work in a completely different way. As a sound wave moves forward, it makes the air bunch together in some places and spread out in others. This creates an alternating pattern of squashed-together areas (known as compressions) and stretched-out areas (known as a rarefactions ).
Top: Sound waves are longitudinal waves: the air moves back and forth along the same line as the wave travels, making alternate patterns of compressions and rarefactions. Bottom: Ocean waves are transverse waves: the water moves back and forth at right angles to the line in which the wave travels.
This superb Steinway grand piano dates from 1876 and sits in the amazing gallery at the National Trust's Lanhydrock country house in Cornwall, England.
In Arthur C. Clarke’s book Earthlight, the legendary science fiction author of the 20th century conceives of a futuristic weapon that uses electromagnetism to propel a jet of molten metal miles into space, spearing and destroying an attacking battleship. This type of armor-piercing weapon isn’t entirely unheard of. Since World War II, various arms manufacturers have supplied combatants with tools of war called self-forging penetrators (SFPs).
Potentially overshadowing the MOAB as the most lethal non-nuclear weapon in the United States’ arsenal, Project Thor is a technology designed by Jerry Pournelle in the 1950s that would obliterate enemies with bolts from above.
To win a war, it’s still essential to keep the true strength of your forces and the extent of your arsenal hidden from your opponent. The most important military secrets are only disclosed to the select few who can be trusted to carry out the mission . For this reason, the US government can’t divulge complete information about its tools ...
A DEW inflicts damage from a distance by firing an intensely concentrated beam of energy toward a target. Different types of DEWs fire different types of energy, but the most popularized form of directed energy weapon in use today is the high energy laser (HEL).
Between 1949 and 1969, the United States military tested biological weapons on its own people without their knowledge or consent. One such experiment occurred in 1950 when a US Navy ship sprayed billions of tiny microbes into the atmosphere over San Francisco, causing a massive upsurge in illness and potentially killing one resident.
The Greek mathematician Archimedes may have made history over 2,000 years ago as the first person to ever use a directed energy weapon. According to a mysterious legend, during the Roman invasion of Syracuse, Archimedes rapidly constructed a hexagonal mirror when the Roman admiral Marcellus moved his ships out of the range of bowshot.
It’s been well established that subliminal messaging is used extensively in advertising. This type of marketing usually exploits the baser urges of the populace to influence them to buy a product or service. But what if the same principles used in subliminal advertising are also being used by the United States intelligence community for the purposes of espionage or even mind control?