Ch 2 The Ordered Universe Classwork Notes Keep until due date Must be in order Must have title page...
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Transcript of Ch 2 The Ordered Universe Classwork Notes Keep until due date Must be in order Must have title page...
Ch 2 The Ordered Universe
• Classwork Notes • Keep until due date• Must be in order
• Must have title page with contents list
The Night Sky
1. Why do planets seem to wander in the night sky?
Orbit the sun. we are the 3rd planet therefore 5 planets are outside of our orbit.Retrograde motion
Night Sky
2. North starWabbling causes precession north star changes over time
Night Sky
3 StonehengeCircle 0f sarsen stone 20 miles away from the hills, 50
tons 1 ton = 2000 lb 50 tons = 100,000lb1lb = 454 g = .5kg 50 tons = 105 lb = 5 x 10 4 kg = 5 x 107 g
Night Sky
4 Spread of disease Swin flu! It’s the common cold on steroids. Ticks!
Mosquito! Fleas!Ancient AstronautsDo you think “People” aliens built the Pyramids? If
so or not describe an exp. To prove it.
Topic: The Birth of Modern Astronomy
Objective: Notes on 4 major people who influenced the belief of the solar system
Standard: Physics Motion/Newton1. Relative position v. Actual of stars (fixed background2. What causes the streaky motion of meteors and
others?3. Ptolemy and Copernicus4. Brahe and Kepler5. Elliptical and the other’s
The Birth of Modern Astronomy
1. Relative position v. Actual position of stars (fixed background
Stellar Aberration
The aberration of starlight was discovered in 1727 by the astronomer James Bradley while he was searching for evidence of stellar parallax, which in principle ought to be observable if the Copernican theory of the solar system
1.
• The observed displacement was greatest for stars in the direction perpendicular to the orbital plane of the Earth
The Birth of Modern Astronomy
Apparent Displacement of Stars• Newton's days, astronomers have tried to
find how far the stars were by the parallax method,
• using the diameter of the Earth's orbit as a baseline.
The Birth of Modern Astronomy
• …measure the positions of stars at times half a year apart
• Representing two positions of the Earth separated by 300,000,000 km
• check whether the positions of stars in the sky changed.
• Indeed, the positions did change. The trouble …observations did not make much
sense!
The Birth of Modern Astronomy
• Jean Picard, French astronomers, • made possible precise observations • “crosshairs in the telescope eyepiece”• In 1680, the observed positions of stars were not always the
same. • John Flamsteed, the astronomer royal of Britain--head of
the Royal Observatory in Greenwich--confirmed those shifts.
• Polaris, the pole star, seemed to travel annually around an ellipse whose width was 40",
40 seconds of arc.
The Birth of Modern Astronomy
2. What causes the streaky motion of meteors and others?
"shooting star," glowing trail, celestial debris entering our atmosphere. Meteors things in space, meteorite in our atm. Meteoroid on the ground
The Birth of Modern Astronomy
The Birth of Modern Astronomy
3. Ptolemy and CopernicusPtolemy propounded the geocentric theory in a
form that prevailed for 1400 years. observations -Alexandria in Egypt AD 127-41.Pty -by 'Theon the mathematicianTheon of Smyrna
The Birth of Modern Astronomy
3. Copernicus• 1473-1543 Copernicus is said to be the
founder of modern astronomy. • He made his celestial observations from a
turret situated on the protective wall around the cathedral, observations were made "bare eyeball," De Revolutionibus, the earth rotated on its axis and around the sun
The Birth of Modern Astronomy
4. Brahe and Kepler
• Brahe never really accepted the Copernician , • The five known planets circled the Sun• Brahe's theory of planetary motion was incorrect
Johannes Kepler, used the data that he collected about the stars in developing the correct description of planetary motion.
The Birth of Modern Astronomy
5. Elliptical and the other’s
The Birth of Mechanics
Left hand side 1. Mechanics2. Galileo Galilei3. Speed, Velocity, Acceleration4. G-force
The Birth of Mechanics
1. MechanicsThe motion of objects,Speed 65 mphVelocity 65 mph EastAcceleration 2 mph2 westForce 6.5 N does need a directionMomentum 600 lb mi/h
The Birth of Mechanics
2. Galileo GalileiItalianPhysicist late 16th centuryTelescope, jupiters moons reasoning for Elliptical orbitsEllipse have “two centers” Focus , foci
The Birth of Mechanics
3. Speed, velocity, accelerationSpeed = distance / Time units m/sVelocity = displacement / time What is the difference between distance and
displacement? Acceleration = Velocity / time
= displacement/ time2
The Birth of Mechanics
4. G-force Gravitational force need mass to apply G = g =
Newton’s Laws
1. First law- constant unless force applied2. Second Law- F= ma units kg m/s2
3. Third Law- F12 =-F21
4. Laws at work shuttle launch – 17,000 km/hr
Momentum
1. P = mv2. Conservation of linear momentum3. Angular momentum4. Inertial guidance systems
1. p = mv
p = momentum units kg m/s or Ns
Mass = kgVelocity or speed both v = 1 x 10-15 m/sp = 102 Ns
P/v = m = 102 Ns / 1 x 10-15 m/s102-(-15) = 10 17 kg
2. Conservation of linear momentum
• Linear = line linear momentum in 2-dimensionsp= # x + #y Steps 5 m north then steps 2 m east
5m x + 2m y = DV = D/t t= 3 s V= 5m/3s x + 2m / 3s y m= 3 kg P= mv =3 kg {5m/3s x + 2m / 3s y} P= 5kgm/s x + 2kgm/s y
3. Angular momentum
• p= #cos θ x + #sin θ y • Momentum has some curve • Constant momentum occurs when angle
doesn’t change
4. Inertial guidance systems
• Gyroscope, …. Segway• Keeps the object from falling over• The gyroscope spins to keep it up right• There are three circles spinning for the 3
dimensions
Universal Force of Gravity
1. Gravitational constant G2. Weight v mass3. G v g
1. Gravitational constant G
Bottom p. 52 Equation Form Also Symbolic formForce on object (Netwon) =
= G (Nm2/kg2) m1 m2/ D2
10-11 = .0000000001
2. Weight v mass
Weight = changesMass = sameW = mgg= plant Earth gravity = 9.8 m/s2
W = 150 lb 1st change to kg = 68.1 kgm= w/g= 68.1 kg / 9.8 m/s2
you cant do this weight is in ……newtonsW = mg = 68.1 kg 9.8 m/s2 = 667.38 N
3. G v g
• G world universe planet Earth• g Planet Earth • G 6.7 x 10 -11 (Nm2/kg2) • g = 9.8 m/s2
• The differences between the two g’
Key terms
• Mechanics • Speed• Velocity• Acceleration• Netwon’s laws of motion• Uniform motion• Force• Mass• Gravity• Netons Law of universal gravitation• Weight
Review q 1-11
Discussion Q 1-8
Problems 1-8
Investigations 1-8
www resources
• 1. www kelper.arc.nasa.gov/johannes.html• 2. www.wam.umd.edu/~tlaloc/archastro• 3. Es.rice.edu/ES/humsoc/Galileo