Exam 2 Flashcards
Ch. 5-11
Density
mass / volume
(m divided by v)
Pressure
Force / area
(f divided by a)
How would you describe water pressure?
the greater the depth, the greater the pressure.
depth dependent and not volume dependent.
How does a water tower work?
the force of gravity acting on the water in a tall tower produces pressure in pipes below that supply many homes with reliable water pressure.
What is Archimedes’ Principle?
Bouyant force is equal to the weight of the displaced fluid. It can also be understood by pressure differences.
True or false: Archimedes’ Principle only applies to liquids.
False, AP applies to liquids and gasses (fluids).
True or False: More dense substances sink to the bottom while less dense substances float to the top.
True
Define gas pressure
Gas pressure is a measure of the amount of force per area that a gas exerts against containing walls.
Explain atmospheric pressure
caused by the weight of the air.
varries from one locality to another.
not uniform.
measurements are used to predict weather conditions.
what is a barometer?
a device used to measure atmospheric pressure
what is an aneroid barometer?
a small portable instrument that measures atmospheric pressure
What is a manual water pump?
Pumps air out of the pipes.
air pressure pushes the water up into the pipe.
what is a mechanical water pump?
Mechanical water pumps depend on electricity instead of atmospheric pressure (no 33.8m limit).
What is the density of air?
1.293 g/L
What does Bernoulli’s principle (continuous flow) tell us?
Where the speed of fluid increases, internal pressure in the fluid decreases. This applies to a smooth, steady flow.
How does a straw work?
as you suck on the straw, the air pressure draws the liquid up the straw.
Would an astronaut be able to use a straw in space?
no, because there is no air pressure to draw the liquid up.
What are the measurements of atmospheric pressure?
14.7 psi (pounds per square inch)
760 mm Hg (millimeters of mercury)
30 in Hg (inches of mercury)
1 atm (atmosphere)
What is Absolute Zero?
The lowest limit of temperature.
As temperature of a gas changes, ___________ of a gas changes.
Volume
What is the definition of heat?
Energy being transferred from one object to another.
What is the natural direction of heat flow?
From a warmer substance to a cooler substance.
What is Thermodynamics?
The movement of temperature.
Explain the first law of thermodynamics.
When heat is added to a system:
it can raise the temperature
it can be used to do work
Energy can neither be created nor destroyed.
Explain the second law of thermodynamics.
Heat can flow from cold to hot only when work is done on the system or by adding energy from another source. Heat never spontaneously flows from a cold substance to a hot substance.
What is the definition of specific heat capacity?
the quantity of heat required to change the temperature of one unit mass of a substance by one degree.
What does the high specific heat capacity of water do or have?
Has a higher capacity for storing energy than almost any other substance.
Makes it useful as a coolant.
Explain Thermal expansion.
Due to rise in temperature of a substance, molecules jiggle faster and move farther apart.
Most substances expand when heated and contract when cooled.
What is the expansion of water?
Water expands when it turns to ice. Ice has open-structured crystals which make it less dense than water.
What are the three processes of thermal energy transfer?
Conduction, Convection, and Radiation
What is conduction?
the transfer of internal energy within a substance. Conduction occurs predominately in solids where the molecules remain in relatively restricted locations.
What is a good conductor?
A poor insulator (i.e. metals and glass)
What is a bad conductor?
A good insulator (i.e. wood, wool, straw, paper, Styrofoam, cork, etc.)
Give an example of convection.
Visible shimmer of air above a hot stove or above asphalt on a hot day. Visible shimmers in water.
What are convection currents produced by?
Unequal heating of land or water.
Explain the wavelength frequency in relation to temperature.
Warmer objects emit a shorter wavelength light. Cooler objects emit a longer wavelength light.
Explain Climate change.
Energy is absorbed from the sun, part of which is reradiated by earth as longer wavelengths of terrestrial radiation. Because of the greenhouse effect, those reradiated waves do not leave the atmosphere.
True or False: Without the greenhouse effect, life on earth would be fine.
False, life would not exist on earth if there was not a greenhouse effect.
Some gasses called ___________ gasses trap even more heat.
Greenhouse
When we burn fossil fuels, we are ___________ the CO2 in the atmosphere.
increasing
Changes in climate patterns produce…
stronger storms, more droughts, and changes in the local climate of an area.
What are the three common phases of matter?
solid, liquid, and gas
What is the fourth uncommon phase of matter?
Plasma
True or false: when matter changes from one phase to another, energy is transferred.
true