The drawing shows two crates that are connected by a steel wire that passes over a pulley. The unstretched length of the wire is 1.5 m, and its cross-sectional area is 1.3 3 1025 m2 . The pulley is frictionless and massless. When the crates are accelerating, determine the change in length of the wire. Ignore the mass of the wire.
Unit 8 Notes Atmospheric Pressure -Pressure is a force/unit area vertical pressure is influenced by gravity - Surface pressure, the standard sea-level air pressure is 1013.25 mb (millibars =101.325 hectopascals), about 14.7 lb/in2. -Pressure lines on surface weather chart are called isobars, and are drawn at 4 mb intervals. -Force- weight of atmosphere pressing down on Earths surface -When air is sinking, pressure is higher -When air is rising, pressure is lower Measurement of Pressure: The Barometer -Invented by Torricelli, a liquid-in-glass barometer. Standard barometer uses mercury. -Standard sea-level pressure is 760 mm (29.92”) -Aneroid barometer, like altimeter in airplanes, uses partial vacuum instrument to measure pressure.
