Use kg, kg, mean Sun distance km, and m /s…

PHYSICS · Multi-part · Fermi University Physics · Mechanics & Dynamical Systems · Rotation, rigid bodies and accelerated frames · Gravitation and central-force motion

Action and Symmetry, Ch Non-inertial frames from one Lagrangian

Problem

Use Mmoon=7.35×1022M_{\rm moon}=7.35\times10^{22} kg, M⊙=1.989×1030M_\odot = 1.989\times10^{30} kg, mean Sun distance d⊙=1.496×108d_\odot = 1.496\times10^{8} km, and GNM⊕=3.986×1014G_{\rm N}M_\oplus = 3.986\times10^{14} m3^3/s2^2. ((a)) Estimate the ratio of the lunar to the solar tidal acceleration at the Earth's surface at the moment the Moon is at its farthest point (apogee), dmoon=4.055×105d_{\rm moon}=4.055\times10^{5} km, treating both bodies as point masses. ((b)) A free-floating experiment sits inside a satellite in geostationary orbit, radius r=42 164r=42\,164 km from the Earth's centre. Using the point-mass tidal-tensor magnitude ∣T∣≈2GNM⊕/r3|T|\approx 2G_{\rm N}M_\oplus/r^3, estimate the greatest length the experiment may have if the tidal acceleration between its two ends is to stay below a tighter tolerance, atol=1.0×10−8a_{\rm tol}=1.0\times10^{-8} m/s2^2.

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