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Universal Gravity. Chapter 8. Kepler’s Laws of Planetary Motion. The orbit of each planet is an ellipse with the sun at one focus. Kepler’s Laws of Planetary Motion. Kepler’s Laws of Planetary Motion.
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Universal Gravity Chapter 8
Kepler’s Laws of Planetary Motion • The orbit of each planet is an ellipse with the sun at one focus.
Kepler’s Laws of Planetary Motion 2. The line segment joining a planet to the sun sweeps out equal areas in equal time intervals.
Kepler’s Laws of Planetary Motion The square of the period of revolution of a planet about the sun is proportional to the cube of the semimajor axis of the planet’s elliptical orbit.
r Kepler’s Laws of Planetary Motion T – Period of one orbit r – Distance of the semimajor axis
TA rA Compare Planet A to Planet B TB rB
( ) ) ( 2 3 TA TB rA rB = Compare Planet A to Planet B
Compare Saturn to Earth Find out how long Saturn takes to make one orbit. Earth TE = 1 year rE=1.50X1011m Saturn TS = ? years rS=1.43X1012m (Table 8.1 Page 178 )
( ) 3 ( ) 2 TS TE rS rE = ( ) 3 rS rE = 2 TS TE
( ) ) 3 ( 3 rS rE = 1.43X1012m 1.50X1011m = 2 2 TS TS (1y) TE TS = 29.4 years
Homework: 8-1 Practice Problems: 1-4 Pages: 180-181 Due: 12/13/02
Homework: 8-2 Problems: 41-44 Pages: 195 Lab Write-up Due: 12/16/02