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BEHAVIOR OF GASES. PRESSURE. The amount of force exerted per unit area. Pressure = force / area. Unit on pressure is PASCAL (Pa). PASCAL = Newton / meter 2. The atmosphere on Earth exerts pressure on everything. How much pressure?. About 100,000 Pa!!! (~100kPa).
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PRESSURE The amount of force exerted per unit area
Unit on pressure is PASCAL (Pa) PASCAL = Newton / meter2
The atmosphere on Earth exerts pressure on everything. How much pressure? About 100,000 Pa!!!(~100kPa)
This means that in every square meter, 100,000N of pressure is exerted. 100,000N = weight of a large truck
As you move farther from the earth, the pressure becomes MUCH less. Which layer would have the least pressure? Why?
Pressure depends on how often the particles hit the surface More times = more pressure
Characteristics of Gases • Negligible Volume (very compressible) • Gases are in constant motion • Collisions are completely elastic • No forces off attraction or repulsion • Kinetic energy of a gas is directly proportional to the temperature
BOYLE’S LAW For a given amount of gas at a constant temperature the volume of the gas varies inversely with pressure.
CHARLES’S LAW Volume of a gas increases if the temperature increases (pressure staying constant)
How could Charles’s Law be used to explain why hot air balloons fill up.
If temperature is constantwhen V decreasesthenP _________ INCREASES
If pressure is constantwhen T increasesthenV _________ INCREASES
What happens when you relax in a swimming pool? You float!!! Duh…but why?
BUOYANCY The ability of a liquid or gas to push up on an object placed in it (you in a swimming pool)
If the buoyant force is greater than the weight, then object FLOATS! If not…it sinks.
DENSITY The relationship of the mass (weight) to how much space it takes up (volume)
ARCHIMEDE’S PRINCIPLE The buoyant force on an object in a fluid is equal the weight of the fluid displaced