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Section 12.3. Orbital Motion of Satellites and Kepler’s Laws. Satellites move in circular (or more generally, elliptical) orbits Compute their period and speed by applying Newton’s 2 nd Law in the radial direction. . m. . M. Orbital speed. Orbital period. Example.
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Section 12.3. Orbital Motion of Satellites and Kepler’s Laws • Satellites move in circular (or more generally, elliptical) orbits • Compute their period and speed by applying Newton’s 2nd Law in the radial direction m M Orbital speed Orbital period
Example Venus rotates slowly about its axis, the period being 243 days. The mass of Venus is 4.87 x 1024 kg. Determine the radius for a synchronous satellite in orbit about Venus. Solution: Given: MV = 4.87 x1024 kg, TV = 243 days Recognize: Synchronous means that the period of the satellite equals the period of Venus, Ts=TV Convert TV to seconds and find rs
Kepler’s Laws of Orbital Motion • 1st Law - planets follow elliptical orbits with the Sun at one focus of the ellipse • 2nd Law - the radius vector from the Sun to the planet sweeps out equal areas in equal time • 3rd Law - the orbital period of a planet is proportional to the radius to the 3/2 power (derived for circular orbit – just replace r by a)