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65 Cards in this Set
- Front
- Back
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Why did Copernicus propose his theory?
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The previous one seemed too busy. He thought it was too complicated and it should be simpler.
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The most characteristic feature of science is
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the mutually supporting relationship between theory an observation
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What was the theory that proved useful for Kepler as he eveloped his own idea?
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Copernicus's theory
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Is the atomic theory know, for certain, to be true?
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No
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Carbon atoms are about 25% lighter than oxygen atoms (weight ratio is 3 to 4). What is the weight ratio of the carbon dioxide CO2?
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1C, 2O
1 x 3 / 2 x 4 = 3/8 or 3 to 8 |
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Which has the largest mass?
a. an oxygen atom b. a hydrogen atom c. an electron d. a proton e. a water molecule |
a water molecule
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How old are a baby's atoms? Are they older than an adult's atoms? What about a baby's DNA molecules?
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Atoms will be the same always (no age).
DNA will be "older" in an adult. |
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You are on earth and throw an apple with a speed of 5 m/s out of a window that is 10 m high. What is the apple's acceleration?
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a = 9.8 m/s2
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The gravitational force between any two objects is dependent on
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the mass of the two objects and the distance between the two objects
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Will your weight be less on the moon? Mass?
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Weight, yes.
Mass, no. |
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Consider an asteroid coming in along a straight-line path with a very high speed on a trajectory that would pass by the earth as shown. What do you think will most likely happen as it passes the earth?
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It will bend slightly toward the earth and then head back out into space with a new straight line path.
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Suppose you lift a book weight 10 N from the floor to a shelf 2m above the floor. You move the book at a constant speed. While you are lifting it, how large is the average net force on the book?
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0 N
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How large is the net force by your hand on the book?
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10 N
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What does the 2n law tell us about the efficiency of heat engines?
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Never 100%
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If dropped from the same height and neglecting air resistance, which will have a larger speed right before hitting the ground?
a. brick b. feather c. bowling ball d. they will have the same velocity |
they will have the same velocity
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You roll a ball. It soon stops. How would Aristotle interpret this? Galileo?
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Aristotle would say the object's "natural place" was at rest. Galileo would say some outside force would have to have taken place on the object.
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If you throw your shoe in outerspace with a speed of 3m/s it will soon come to a stop. True or False?
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False
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T/F
There is no difference between speed and velocity? |
False. Velocity has speed AND direction. Speed doesn't matter with direction.
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As you drive, I notice that your car covers longer and longer distances per second. What can be concluded about your speed, velocity and acceleration?
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Speed: increases
Velocity: increases Acceleration: in the direction of velocity |
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You are traveling at a constant 70 m/hr. What is your acceleration?
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There is no acceleration if it's constant. 0 mi/hr
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energy that tends to go through transformations and end up as thermal energy
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non-thermal forms of energy
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How do we validate the law of conservation of energy?
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1. heat can do work and can be created by work.
2. Heat is actually a form of thermal energy |
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the study of energy
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thermodynamics
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flows spontaneously (without external assistance) from a higher-temperature object to a lwer-temperature object. It will not spontaneously flow the other way.
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thermal energy
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energy flows from _____ to _____, NEVER the other way
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hot to cold
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any device that uses thermal energy to do work is known as
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a heat engine
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it's easy to get heat from...
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work
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it is more difficult to get _____ from heat
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work
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use a portion of the thermal energy that naturally flows from a high to get a low temperature and convert it to work
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heat engines
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obtained when the heat is allowed to flow from a high temperature to a low temperature
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mechanical energy
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in addition to doing work, a heat engine ejects a lot of:
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thermal energy (exhaust)
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Is all of the energy input used to do work?
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No
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Heat engines are always...
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less than 100% efficient
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The 2nd law of thermodynamics states:
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heat engines are always less than 100% efficient
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efficiency depends on...
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the input temperature and the output temperature
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any device that uses thermal energy to do work is known as
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a heat engine
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it's easy to get heat from...
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work
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it is more difficult to get _____ from heat
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work
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use a portion of the thermal energy that naturally flows from a high to get a low temperature and convert it to work
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heat engines
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obtained when the heat is allowed to flow from a high temperature to a low temperature
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mechanical energy
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in addition to doing work, a heat engine ejects a lot of:
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thermal energy (exhaust)
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Is all of the energy input used to do work?
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No
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Heat engines are always...
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less than 100% efficient
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The 2nd law of thermodynamics states:
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heat engines are always less than 100% efficient
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efficiency depends on...
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the input temperature and the output temperature
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a quantitative measure of the disorganization a the microscopic level
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entropy
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does the natural process tend to move toward a state of greater order or disorder?
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disorder
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does the 2nd law forbid entropy from decreasing?
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no, it simply says the probability is extremely low
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consumes about 40% of the energy used by the united states
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transportation
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consumes about 70% of the nation's oil
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transportation
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burns fuel to generate heat that is partially transformed into useful work
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internal combustion
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what is burned to produce an internal combustion?
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a fuel-air mixture
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when fuel provides thermal energy to another substance that does work it is called:
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external combustion
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how much of the exhaust is removed by the radiator? what happens to the rest?
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about 1/2
it's released as pollution |
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what is the main source of global warming?
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CO2
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what is the ideal efficiency?
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30%
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actual efficiency ?
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25%
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why do we lose energy?
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incomplete combustion, formation of NOx, friction and thermal losses
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what is the entire efficiency of an automobile?
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13%
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what are the pros of an electric vehicle?
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they are emission free if solar or wind generated electricity
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what are the cons of electric vehicles?
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emissions if electricity generated from fossil fuel, heavy, costly, and only have 100 miles range with hours of charging
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substance which the disturbance moves
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medium (rope, slinky, water)
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disturbance that travels through a medium in such a way that energy travels through the medium but mass does not
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wave
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peak to peak, trough to trough
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wavelength
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number of vibrations in that any particular part of the medium experiences in a second
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frequency
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