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Satellites and Weightlesness. Descending in an elevator causes partial weightlessness…this is the same thing that occurs in space as you are ‘falling’ toward Earth. We can use a c = v 2 /r so since F=ma, Gm 1 m E /r 2 = m sat v 2 /r See Example 5-15 p130. …a falling elevator.
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Satellites and Weightlesness Descending in an elevator causes partial weightlessness…this is the same thing that occurs in space as you are ‘falling’ toward Earth. We can use ac = v2 /r so since F=ma, Gm1mE /r2 = msat v2 /r See Example 5-15 p130
…a falling elevator • See page 131
Kepler’s Laws and Newton’s Synthesis • Kepler’s laws of planetary motion… • 1st…The path of each planet about the Sun is an ellipse with the Sun at the focus. • 2nd…Each planet moves so that an imaginary line drawn from the Sun to the planet sweeps out equal areas in equal periods of time. • 3rd…The ratios of the squares of the periods of any two planets revolving about the Sun is equal to the ratio of the cubes of their mean distances from the Sun.
See the chart on p133… • So lets examine Kepler’s 3rd law… • (T1/T2)2 = (r1/r2)3 so… • R13 /T12 = r23 /T22 • See Example 5-16 and 5-17 • Make sure you know the definition of geosynchronus…
Other Details about Orbits • Perterbations are deviations from perfect elipses…the planets do this at times. • The sun, or any central star wobbles from the gravitation of the planets.
Homework • P142 39-42, 51-54