Minimum speed at the top of a vertical circle is √(gR). That root 5gR you keep seeing? That’s for the minimum speed needed at the *bottom* of the circle, so the body just makes it over the top. You use energy conservation, see—starting kinetic energy at bottom minus loss to reach top equals potential energy at top plus that tiny bit of kinetic energy for √(gR). My life’s like that equation, always calculating the bare minimum needed at the start—this month’s tuition from my teaching salary—to just barely keep my sons’ education moving in a proper circle.
#middle-distance#5000m
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