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
When moving from a solid to a liquid or a gas, energy (heat) is ____________.
Absorbed
Energy (heat) is _____________ when moving from a gas to a liquid or a solid.
Released
What is the equation for volume?
volume = length x width x height
How do you find the volume of an irregular shaped object?
Use water displacement.
What causes a hot air balloon to rise?
Hot air balloons rise because the hot air inside is less dense than the cooler air outside.
What is an atom?
the basic building blocks used to make everything in nature.
What are atoms made up of?
A nucleus that contains protons and neutrons, and particles that orbit around the nucleus are called electrons.
True or false: protons have a positive charge.
true
true or false, neutrons have a negative charge.
False, electrons have a negative charge. Neutrons have no charge.
What is the equation for Electical Force?
EF = k(q1q2)/(d^2)
True or false: the electrical force depends on the amount of mass.
False, that is the gravitational force. the electrical force depends on the amount of charge (q).
Like the gravitational force, the electrical force ______________ as the charges are separated.
decreases
Unlike the gravitational force, the electrical force only works over _______ distances.
short
True or false: Electrical force can be attractive or repulsive.
true
What does k equal in the Electrical Force equation?
9,000,000,000
What is the gravitational force equation?
GF = K(m1m2)/(d^2)
True or False: Gravitational force can be attractive or repulsive.
False, gravitational force is only an attractive force.
What does the K equal in the Gravitational Force equation?
0.0000000000667
What happens if negative charges are attracted to positive charges?
The electrons stay in orbit around the nucleus.
What happens when positive charges are repelled by positive charges?
nuclear power
__________ charges are repelled by negative charges.
Negative
True or False: Opposites attract.
True
When you push two negative charges together, ____________ ________ increases. When released, the charges ________ ________ from one another.
potential energy; move away
When you pull a negative charge away from a positive charge, the _______________ charge has potential energy. When you release the negative charge, it will ______ ________ ___________ the positive charge.
Negative; move back toward
What is Electrical Potential?
Measured in Volts, it is the amount of potential energy for each charge.
What is Electrical Current?
Measured in Amperes, it is the amount of charge flowing through the wire per second.
What is Resistance?
a measure of how difficult it is for the electrons to flow through a wire.
True or False: Conductors have a low resistance
true
true or false: Insulators have a low resistance
false, insulators have a high resistance
true or false: superconductors have no resistance
true
true or false: semiconductors become conductors if prepared correctly
true
Explain High-Speed Maglev Trains
They are levitated by repulsion of magnets. there is some use of superconductors on board the train (cooled by liquid nitrogen).
What is the difference between the electrical force and the magnetic force?
The electrical force has positive and negative charges and can have an individual electron or an individual nucleus.
The magnetic force has north and south poles and cannot have a north pole without a south pole.
What does the electromagnetic force encompass?
The electrical and magnetic force.
What are the four fundamental forces of physics?
Gravitational, Electromagnetic, Strong Nuclear, and Weak Nuclear
If an ____________ current flows through a wire, the wire becomes a __________.
electrical; magnet
If a _______ ___ ______ spins in a magnetic field, _____________ will flow through it.
coil of wire; electricity
On which temperature scale does water freeze at 0 degrees and boil at 100 degrees?
Celsius
if you touch an ice cube, which direction does heat flow?
from your finger to the ice cube
Which of these is a unit that can be used to measure heat?
a. Kelvin
b. Joule
c. Watt
d. Newton
Joule
Is it possible to reach a temperature of absolute zero?
no
Entropy is a measure of ___________.
disorder
As a result of natural processes, the entropy of our world is ______________.
Increasing
Which type of heat transfer occurs primarily in liquids and gases?
convection
which type of heat transfer can occur anywhere, even through empty space?
radiation
in convection currents…
warm air rises
radiation with a long wavelength has…
low energy.
What is Amplitude?
distance from the midpoint to crest or trough. Determines the volume of a sound or the brightness of a light.
What is a wavelength?
distance from the top of one crest to the top of the next crest, or distance between successive identical parts of the wave. determines the color of light, etc.
What is frequency?
the number of variations in a given time. Determines pitch.
Transverse wave v. Longitudal wave
longitudal is a sound wave
Transverse is a light wave
How does sound move?
in longitudal waves
What is reflection?
the returning of a wave to the medium through which it came.
What is refraction?
the bending of a wave due to a change in the medium and/or speed
sound waves refract when parts of the wave fronts:
- travel at different speeds
- are affected by uneven winds
- when air near the ground is warmer than the air above
What is the doppler effect?
The change in frequency as measured by an observer due to the motion of the source or the listener
What is selective transmission of color?
the color of a transparent object which depends on the color of the light it transmits.
What is selective reflection of color?
most objects dont emit light, but reflect light.
a material may absorb some of the light and reflect the rest.
true or false: objects submerged in water appear closer to the surface.
True, due to refraction of light.
What are the additive primary colors?
Red, Blue, and Green
- R + B = Magenta
- R + G = Yellow
- B + G = Cyan
Explain Complementary Colors
Opposite colors
The addition of any color to its opposite color results in white.
True or false: magenta, yellow, and cyan are considered subtractive primary colors
true
True or False: Green plants reflect green light and absorb the opposite color blue.
False, they absorb the opposite color which is red. Plant grow lights are concentrated more on the red end of the spectrum because of this.
The visible spectrum consists of 7 colors: ROYGBIV. When grouped together they appear to be ________.
white
Why is the sky blue?
Nitrogen and oxygen scatter violet and blue hues the most. Our eyes mostly detect blue.
Why are clouds white?
Clouds have a variety of water droplet sizes. these scatter all wavelengths of color and give off white as a result.
Why are thunderstorm clouds black?
Large clusters of raindrops absorb nearly all the light.
Why are sunsets red?
At sunset, sunlight must travel further through the atmosphere. red is scattered the least and able to travel this distance.
Explain Dispersion
Process of separation of light into colors arranged by frequency.
