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ANGULAR AND TANGENTIAL SPEED
ANGULAR AND TANGENTIAL SPEED  PDF

ANGULAR AND TANGENTIAL SPEED

The angular speed indicates the angular displacement variation per time unit; in the SI it is measured in rad/s (radians per second). The tangential speed is the actual speed of a turning point in a circular movement (constant radius) and is measured in meters per second (m/sec.).


VACUUM AND ATMOSPHERIC PRESSURE
VACUUM AND ATMOSPHERIC PRESSURE  PDF

VACUUM AND ATMOSPHERIC PRESSURE

A vacuum (from the Latin vacîvus) is the total absence of matter on a specific area or location, or the absence of content inside a container. By extension, the condition of an area where the particle density is very low is also called vacuum, for example, interstellar space, or a closed cavity in which the pressure of air or other gases is less than atmospheric pressure.

Atmospheric pressure is that which is exerted by the atmosphere or air upon the Earth. At room temperature and normal atmospheric pressure, one cubic meter of air contains about 2 × 1025 molecules moving at an average speed of 1600 kilometers per hour.

One way to measure the atmospheric pressure is to use a mercury barometer; its reading is expressed in terms of the height of the cross section of the mercury column, and 760mm in height. We say that a standard atmosphere is equal to 760 mmHg. For our convenience we will use Torricelli unit (symbol Torr) as the pressure measurement, 1 Torr = 1 mm Hg, so that 1 atm = 760 Torr, therefore 1 Torr = 1/760 of one standard atmosphere, or 1 Torr = 1.136 × 10-3 atm.