Before we introduced the Friedmann equation, we gained some intuition with a Newtonian example of an expanding sphere of uniform density that feels its own gravity. Suppose the sphere is currently static; it has expanded to its maximum size and is about to recollapse. Given that its total energy per mass is U, and its density is currently \rhoρ, what is its current size? Write your answer in meters, using one decimal place. Values: U = -82 J/kg \rhoρ = 545 x 105 kg/m3

Before we introduced the Friedmann equation, we gained some intuition with a Newtonian example of an expanding sphere of uniform density that feels its own gravity. Suppose the sphere is currently static; it has expanded to its maximum size and is about to recollapse. Given that its total energy per mass is U, and its density is currently \rhoρ, what is its current size? Write your answer in meters, using one decimal place. Values: U = -82 J/kg \rhoρ = 545 x 105 kg/m3

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