2011 Pearson Education, Inc. Units of Chapter 2 2.1 Ancient Astronomy 2.2 The Geocentric Universe...
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Transcript of 2011 Pearson Education, Inc. Units of Chapter 2 2.1 Ancient Astronomy 2.2 The Geocentric Universe...
© 2011 Pearson Education, Inc.
Units of Chapter 2
2.1 Ancient Astronomy
2.2 The Geocentric Universe
2.3 The Heliocentric Model of the Solar SystemThe Foundations of the Copernican Revolution
2.4 The Birth of Modern Astronomy
© 2011 Pearson Education, Inc.
Units of Chapter 2, continued
2.5 The Laws of Planetary MotionSome Properties of Planetary Orbits
2.6 The Dimensions of the Solar System
2.7 Newton’s Laws
2.8 Newtonian MechanicsWeighing the Sun
© 2011 Pearson Education, Inc.
White Board Question• What are some ancient structures that people used
the sun and stars to help keep track of time and seasons?
© 2011 Pearson Education, Inc.
2.1 Ancient Astronomy
• Ancient civilizations observed the skies
• Many built structures to mark astronomical events
Summer solstice sunrise at _____________:
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2.1 Ancient AstronomySpokes of the _________________________in Wyoming are aligned with the rising and setting of the Sun and other stars
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2.1 Ancient Astronomy
This temple at _______________, in Mexico, has many windows that are aligned with astronomical events
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2.2 The Geocentric Universe
Earth based
Ancient astronomers observed:
Five planets:
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2.2 The Geocentric UniverseSun, Moon, and stars all have simple movements in the sky
Planets:• Move with respect to fixed stars
• Change in brightness
• Change speed
• Undergo retrograde motion
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Golden Age600 BC-AD 150Aristotle
• _______ philosopher (384-322 BC)
• Earth is _____________• Casts a curved shadow when
passes between _________ and ______
His belief was abandoned during the Middle Ages
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_________________276-194 BC
• First successful attempt to figure out the size of the earth
____________________2nd Century BC
• Divided stars into six groups according to brightness
• Method for predicting lunar eclipses
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________centric model• _______________________
orbit the earth• _________________(stars)
orbits the earth• Incorrect
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2.2 The Geocentric UniverseEarliest models had ____________________ at center of solar system
Needed lots of complications to accurately track planetary motions
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Carl Sagan on epicycles
http://www.dailymotion.com/video/xerwsh_carl-sagan-videos-epicycles-of-ptol_tech
Take notes:
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_____________centric Model
• First heliocentric astronomer--Aristarchus (Greek 312-230 BC)
• Earth and other planets orbit the sun
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Heliocentric vs. Geocentric Model
Model Location of Earth
Location of Sun
Who supports
__________Center of the universe Orbits
_______
Heliocentric _________ ________ of the universe
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White board question• On your white board make a Venn Diagram
comparing Heliocentric and Geocentric views of the universe.
Ptolemaic System
• Claudius ______________ wrote a 13 volume work on Greek astronomy
• ___________centric, used ___________ to explain the varying brightness of planets and planet retrograde motions
• Used mathematical terms to explain the heavenly bodies
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2.3 The _____________________ Model of the Solar System
This figure shows retrograde motion of Mars.
_______________ is at center of solar system. Only Moon orbits around Earth; planets orbit around Sun.
© 2011 Pearson Education, Inc.
Understanding retrograde motion
• http://astro.unl.edu/classaction/animations/renaissance/retrograde.html
• Interactive– http://highered.mcgraw-hill.com/olcweb/cgi/
pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78780/Retro_Nav.swf::Retrograde%20Motion
© 2011 Pearson Education, Inc.
White board• Explain retrograde motion to your
neighbor, see if you can write it out
© 2011 Pearson Education, Inc.
Discovery 2-1: The Foundations of the Copernican Revolution
1. ____________ is not at the center of everything.
2. Center of Earth is the center of _________ orbit.
3. All _________________revolve around the Sun.
4. The ________________ are very much farther away than the Sun.
5. The apparent movement of the stars around the Earth is due to the Earth’s __________________.
6. The apparent movement of the Sun around the Earth is due to the Earth’s __________________.
7. ______________________motion of planets is due to Earth’s motion around the Sun.
© 2011 Pearson Education, Inc.
2.4 The Birth of Modern Astronomy
_________________________ invented around 1600
___________________ built his own, made observations:
• Moon has mountains and valleys
• Sun has ___________, and rotates
• ______________has moons Venus has ________________
Galileo and Venus
• How did Venus retrograde motion definitely prove that the sun is at the center of the solar system?
• Turn to your table group and see if you can figure it out
© 2011 Pearson Education, Inc.
2.4 The Birth of Modern Astronomy
_______________cannot be explained by geocentric model
_______________1546-1601Denmark
• Developed instruments to measure the locations of heavenly bodies
• Collected a vast amount of data that Keplar was able to use to build his laws of planetary motion
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2.5 The Laws of Planetary Motion
___________________were derived using observations made by Tycho Brahe
Johannes Kepler1571-1630
• Three laws of planetary motion–Kepler observed:
• Mars orbit was elliptical• As Mars approaches the sun it speeds up and slows down as it goes away from the sun
Three laws of planetary motion1. The path of each planet around the sun is an ellipse
with the sun at one focus.
2. Each planet revolves around the sun so that it sweeps over equal areas in equal amounts of time causing it to travel more rapidly in areas closer to the sun.
3. The square of the orbital period is proportional to the cube of its distance from the sun.
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2.5 The Laws of Planetary Motion
Law 1. Planetary orbits are ________________, Sun at on a
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Time to try it on your own
• An ellipse can be drawn with the aid of a string, a pencil, and two thumbtacks. The wider the separation of the foci, the more elongated, or eccentric, is the ellipse. In the special case where the two foci are at the same place, the curve drawn is a circle.
© 2011 Pearson Education, Inc.
2.5 The Laws of Planetary Motion
Law 2. Imaginary line connecting Sun and planet sweeps out _________________________
Keplar’s 2nd law
http://www.youtube.com/watch?v=5a2mcE-tzKE
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2.5 The Laws of Planetary MotionLaw 3. Square of ____________ of planet’s orbital motion is proportional to cube of _______________________________________
© 2011 Pearson Education, Inc.
More Precisely 2-1: Some Properties of Planetary Orbits
____________________: closest approach to Sun
__________________: farthestdistance from Sun
Another way to say them• The path of the planets about the sun is elliptical in shape,
with the center of the sun being located at one focus. (The Law of _________________________)
• An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of ___________________) http://www.physicsclassroom.com/mmedia/circmot/ksl.cfm
• The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of ________________________)
Easy math
If planet A is 4 units from the sun then what is its orbital period. (a3 = p 2)
Keplar’s laws
http://www.youtube.com/watch?v=5a2mcE-tzKE
http://www.youtube.com/watch?v=GcKiG-CuvtA
Let’s watch different planets in action
• http://astro.unl.edu/classaction/animations/renaissance/kepler.html
__________________
• Mathematician• Invented calculus to solve the gravity
© 2011 Pearson Education, Inc.
2.7 Newton’s Laws
____________________
____________________
____________________explain how objects interact with the world and with each other.
Newton: Three laws of motionLaw 1:
An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called “________________________".
http://teachertech.rice.edu/Participants/louviere/Newton/law1.html
White board question
• If everything in an airplane is traveling at the same speed when do you feel the motion?
Law 2
• Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).
• http://teachertech.rice.edu/Participants/louviere/Newton/law2.html
• Force=____________________________• Forceg=mass x gravitational acceleration
Definitions
• ___________________ is an intrinsic property of an object and remains the same independent of where it is in the universe
• _________________is the downward force experienced by an object as a result of gravitational interaction
A little math
• If Marvin the Martian is 100 lbs on Earth how much would he weigh on the moon if the surface gravity is 17% of that on Earth?
Weight=mass x gravitational accelerationOr weight = weight on earth x specific gravity Now see if you can figure it outW= 100 lbs x .17=17 lbs.
Law 3
• For every action there is an _____________and _______________ re-action.
• http://teachertech.rice.edu/Participants/louviere/Newton/law3.html
Sir Isaac Newton1642-1727
Newton in a nutshellWithout the influence of ____________,
planets would move in a straight line out into space.
The tendency of planets to remain in a straight line and the force of ________________ result in elliptical patterns
Using Newton’s gravity
Basically Force is proportional to the product of the mass
of two objects/distance between them squared so:
If the mass doubles the force ____________ but if the distance doubles then you have ________ the force.
So you can figure weight of an object if you know the distance from earth
© 2011 Pearson Education, Inc.
2.7 Newton’s LawsGravity
On the Earth’s surface, __________________
_________________ is approximately constant, and directed toward the center of Earth
© 2011 Pearson Education, Inc.
2.7 Newton’s LawsGravity
The constant G is called the ______________________________________; it is measured experimentally and found to be
G = 6.67 x 10-11 N m2/kg2
© 2011 Pearson Education, Inc.
But let’s look at an easier way
Fgm1m2/d2
The force of gravity is proportional to the product of the mass of the two objects divided by the distance squared
White board problem
If Marvin is 36 lbs how much is his weight if he is at 2r (distance from Earth)
Weight = 36/22 36/4=9lbs
So if this is true and astronauts at the space station are still within the
earth’s gravity, why do they experience
weightlessness???http://www.youtube.com/watch?
v=2V9h42yspbo
© 2011 Pearson Education, Inc.
2.8 Newtonian Mechanics
_________________: the speed necessary for a projectile to completely escape a planet’s _________________________________. With a lesser speed, the projectile either returns to the planet or stays in orbit.
So what did Einstein have to say about gravity?But what is gravity, what is it that attracts to objects to one
another? http://www.youtube.com/watch?v=O-p8yZYxNGchttp://www.youtube.com/watch?
v=DbhuRcmSkMg&feature=related
Gravity as Curved Space
Curved space
• Einstein noticed ___________________. A beam of light follows the curvature of space
• Planets follow the _________________so if gravity has curvature then anything with
mass will curve the space around it