Final Flashcards
(34 cards)
most associated with the ancient Greek world view (geocentric universe)
Aristotle
rejected the geocentric world view
Aristarchus
accurately determined the size of the earth
Eratasthones
wrote Almgest
Ptolemy
it explained astronomical movements better and was simpler than the geocentric model
Heliocentric model
held the heliocentric worldview
Copernicus
last astronomer without a telescope; provided Kepler with the data needed in order to develop his three laws of motion
Tycho Brahe
Three Laws of Motion; his laws don’t qualify as modern astronomical discoveries because they are descriptive only and don’t take gravity into account
J. Kepler
the shape of the orbit of the planets is an ellipse and the Sun isn’t in the center, but at a foci of the ellipse orbit; the orbit of the earth and other planets (some are more dramatically elliptical than others) is just slightly off form being a circle, so his measurements had to be very precise - this is very impressive
Law of Ellipses
he closer the planet is to the sun in its orbit, the faster it is moving; states that an imaginary line between a planet and the sun sweeps out an area as the planet orbits such that if 3 time intervals are shown are of equal length, then the areas A, B, and C will be equal
the Law of Equal Areas
he farther out the orbit is, the longer it takes for the planet to orbit; to find the orbit time use p^2 = a^3 where p is years and a is astronomical units
The Third Law
used a telescope and challenged the conventional wisdom of the motion of objects and the nature of the heavens; his telescope observations are: the Phases of Venus, the moons of Jupiter, sunspots, and mountains on the moon
Galileo
three laws of motion and the law of universal gravity
Newton
a body at rest or moving in a straight line at a constant velocity will continue in that manner unless acted by a net outside force
Newton’s First Law
F = mass x acceleration; acceleration is change in velocity; change in velocity = either speed up or slow down in the same direction or change direction
Newton’s Second Law
Law of Reciprocal Actions; for every action, there is an equal and opposite reaction; if you push on something, it will push on you
Newton’s Third Law
F = G x M1 x M2/ r^2 the force that holds us on the earth holds the earth in its orbit; if you combine this with newton’s second law, you can derive Kepler’s laws of motion for planets
Newton’s Universal Law of Gravity
light has wave-like properties (wavelength, frequency); when light is traveling, think of a wave, but when it is absorbed, think about it as particles
- visible light is a section of the electromagnetic wave spectrum
- frequency x wavelength = velocity of light
- wavelength - crest to crest or trough to trough
- frequency - wavelength/second
- Wavelengths (from long to short) - radio, infrared, visible, ultraviolet, x-ray, gamma-ray
Wave Nature of Light
a perfect emitter and absorber of electromagnetic radiation
- it produces/emits light because of its temperature
- a cave is a good absorber of light
Blackbody
apply ideally to a blackbody; the color changes as a blackbody gets hotter; cooler the temperature the longer the wavelength (red is cooler, blue is hotter)
- ex of a question: Star A - the wavelength of peak intensity is shorter than Star B, so Star A is hotter
- ex: Star A is blue, star B is red, star A is hotter (blue is hotter than red)
- shorter wavelength is hotter, shorter wavelength is blue
Wien’s Law
light gets brighter as it gets hotter; the hotter it is, the brighter it is; the hotter the object, the shorter the wavelength of peak intensity is
Stefan-Boltzman Law
rainbow; all colors are shown
Continuous Spectrum
certain wavelengths are bright, but in between them there is virtually no light
emission spectrum
rainbow, but has some wavelengths blacked out because there is no light
absorption spectrum
