Sound

Sound is what can be professed by a living organism through its sense of hearing. Physically, sound is vibrational reflex energy that propagates through matter as a wave.

For humans, hearing is limited to frequencies between about 20 Hz and 20000 Hz, with the upper limit generally decreasing with age. Other species may have a different range of hearing. As a signal perceived by one of the major senses, sound is used by many species for detecting danger, navigation, predation, and statement. In Earth's atmosphere, water, and soil practically any physical phenomenon, such as fire, rain, wind, surf, or earthquake, produces (and is characterized by) its unique sounds. Many species, such as frogs, birds, marine and worldly mammals, have also developed special organs to produce sound. In some species these became highly evolved to fabricate song and (in humans) speech. Furthermore, humans have developed culture and technology (such as music, telephony and radio) that allows them to generate, record, transmit, and broadcast sounds.

The mechanical vibrations that can be interpreted as sound can travel during all forms of matter: gases, liquids, solids, and plasmas. However, sound cannot circulate through space. The matter that supports the sound is called the medium. Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called density waves. Through solids, however, it can be transmitted as both longitudinal and oblique waves. Sound is further characterized by the generic properties of waves, which are frequency, wavelength, period, amplitude, intensity, speed, and direction (sometimes speed and direction are combined as a velocity vector, or wavelength and direction are combined as a wave vector). Transverse waves, also known as shear waves, have an additional property of divergence. Sound characteristics can depend on the type of sound waves (longitudinal versus transverse) as well as on the physical properties of the transmission medium.

Gear

A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device possibly another gear wheel so that force can be transmitted between the two strategies in a direction tangential to their surfaces. A non-toothed wheel can transmit some tangential force but will slip if the force is large; teeth put off slippage and permit the transmission of large forces.

A gear can mesh with any device having teeth friendly with the gear's teeth. Such devices include racks and other non-rotating policy; however, the most common condition is for a gear to be in mesh with another gear. In this case revolution of one of the gears necessarily causes the other gear to rotate. In this way, rotational motion can be transferred from one position to another. While gears are sometimes used simply for this reason to transmit rotation to another shaft perhaps their most significant feature is that, if the gears are of asymmetrical sizes, a mechanical advantage is also achieved, so that the rotational speed, and torque, of the second gear are dissimilar from that of the first. In this way, gears provide a means of increasing or decreasing a turning speed, or a torque.

Cattle

Cattle, colloquially referred to as cows, are disciplined ungulates, a member of the subfamily Bovina of the family Bovidae. They are raised as livestock for meat dairy products (milk), leather and as draught animals. In some countries, such as India, they are honored in religious ceremonies and revered. It is expected that there are 1.4 billion head of cattle in the world today.

Cattle were originally known by Carolus Linnaeus as three separate species. These were Bos taurus, the European cattle, including similar types from Africa and Asia, Bos indicus, the zebu,and the extinct Bos primigenius, the aurochs. The aurochs is ancestral to together zebu and European cattle. More newly these three have increasingly been grouped as one species, sometimes using the names Bos primigenius taurus, Bos primigenius indicus and Bos primigenius. Complicating the matter is the capacity of cattle to interbreed with other closely related species. Hybrid individuals and even breeds exist, not only between European cattle and zebu but also with yaks, banteng, gaur, and bison, a cross-genera fusion. Cattle cannot effectively be bred with water buffalo or African buffalo.