Page 158
Pascal’s Law
In 1653, Blaise Pascal came up with the idea that in a fluid at rest, the
pressure on any surface exerts a force perpendicular to the surface and
independent of the direction or orientation of the surface. Any added
pressure applied to the fluid is transmitted equally to every point in the
fluid. Pascal used his idea to invent the hydraulic press. Pascal’s principle
is often used in devices that multiply an applied force and transmit it to a
point of application. Examples include the hydraulic jack, and the
pneumatic cylinder.
Gas Laws
The actions of gases under varying conditions of temperature, pressure,
and volume can be described and predicted by a set of equations, or gas
Laws. These Laws were determined by measurements of actual gases and
are valid for all substances in a gaseous state.
Measurements on gases were first published by Robert Boyle in 1660. He
figured out that if an enclosed amount of gas is compressed until it is half
its original volume while the temperature is kept constant, the pressure
will be doubled. Quantitatively, Boyle’s Law is: PV = Constant, where
the value of the constant depends on the temperature and the amount of
gas present.
Relationships between the temperature of the gas and its volume while
keeping the pressure unchanged were studied by Jacques Charles. He saw
a steady increase in the volume as the temperature went up, finding that
for every degree Celsius rise in temperature, the gas volume increase by
1/273 of its volume at zero degrees C.
To Next Page
Loading...
