Questions
Question 1
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In a circular orbit, is gravity absent, balanced away, or providing the inward acceleration?
Question 2
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Find the circular-orbit speed at radius \(7.5\times10^6\,\mathrm{m}\) around a planet of mass \(6.0\times10^{24}\,\mathrm{kg}\). Use \(G=6.67\times10^{-11}\,\mathrm{N\,m^2\,kg^{-2}}\).
Question 3
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Why does the satellite mass not appear in \(v=\sqrt{GM/r}\) for a circular orbit?
Question 4
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A satellite moves in a circular orbit of radius \(7.5\times10^6\,\mathrm{m}\) with speed \(7.3\times10^3\,\mathrm{m\,s^{-1}}\). Estimate its period.
Question 5
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A satellite has circular-orbit period \(5400\,\mathrm{s}\) around a planet of mass \(5.0\times10^{24}\,\mathrm{kg}\). Find the orbital radius.
Question 6
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A circular orbit has radius \(8.0\times10^6\,\mathrm{m}\) and period \(7000\,\mathrm{s}\). Find the local gravitational field magnitude from the orbit data.
Question 7
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One circular orbit has radius \(r\). Another around the same body has radius \(4r\). Compare their speeds and periods.
Question 8
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Find the radius of a circular orbit around Earth with period \(86164\,\mathrm{s}\). Use \(M_\oplus=5.97\times10^{24}\,\mathrm{kg}\) and \(G=6.67\times10^{-11}\,\mathrm{N\,m^2\,kg^{-2}}\).
Question 9
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A planet's mass is unknown, but a moon is observed in a circular orbit of radius \(1.8\times10^8\,\mathrm{m}\) with period \(3.0\times10^5\,\mathrm{s}\). Estimate the planet mass.
Question 10
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A spherical planet has radius \(R\) and surface field magnitude \(g_s\). Derive the circular-orbit speed and period at radius \(r=kR\), and interpret how both change as \(k\) increases.