Difference between Vacuum and Pressure
Vacuum and pressure may seem like two atmospheric phenomena that are fairly obvious in their manifestations–and in fact, they often are–but it may surprise you to know how often they occur undetected. In this article, we take a look at both phenomenon, and examine their effects on humans.
Definition
Vacuum is defined as a volume of space in which there is hardly any matter present. However, perfect vacuums–in which no particles are present at all–are quite rare, and nearly impossible to achieve even in controlled conditions. In a vacuum, there is generally a lot less pressure present than in the surrounding atmosphere.
Pressure is the force per unit area that air exerts against a surface. In the case of atmospheric pressure, this weight comes from the air above the Earth's surface. Atmospheric pressure is most often approximated by the hydrostatic pressure of the weight of air above the point of measurement. A column of air measuring one square inch as measured from sea level to the highest point of the atmosphere, weighs about 6.3 kilograms.
Implications, Applications And Manifestations
The terms “vacuum” or “free space” are commonly used when referring to test results that occur in a perfect vacuum. “Real” vacuum on the other hand is often referred to as partial vacuum.
Atmosphere pressure may be either low or high, depending on the prevailing atmospheric conditions. In a low-pressure area, the atmospheric pressure as measured at sea level is lower than the air pressure in the surrounding areas. These conditions result from the divergence of winds in the troposphere’s upper levels. High pressure on the other hand occurs in the presence of light winds at the surface of the Earth, which subsides through the troposphere’s lower levels.
Effects On Humans
Extensive studies have shown that humans and animals subjected to even partial vacuum will lose consciousness after only a few seconds, and death by hypoxia will occur in as little as a few minutes. Nonetheless, this occurrence wouldn't result in the dramatic symptoms commonly depicted in fictional cinema.
One of the most common manifestations of pressure is the popping of the eardrums, which commonly occurs when the person is subjected to a rapid change in altitude. This is caused by the action of the ear's mechanism as it tries to compensate for the rise or fall of barometric pressure.
Compare and Contrast
Vacuum
- A volume of space in which there is hardly any matter present
- Perfect vacuums are rare, and almost impossible to achieve
- Will cause loss of consciousness in humans and animals within a few seconds
- Causes eventual death by hypoxia
- Much less pressure present than in the surrounding atmosphere
Pressure
- The force per unit area that air exerts against a surface
- In atmospheric pressure, the weight comes from the air above the earth's surface
- One of the most common manifestations is the popping of the eardrums caused by a rapid change in altitude
