Solution

ID: past-exam-of-the-physics-1-paper-of-the-university-of-oxford/2016/10/ii/solution

For the Hohmann transfer orbit, the inner and outer circular radii are the ellipse's pericentre and apocentre distances, so . The vis-viva equation gives the transfer speed at the inner tangent point,
Both old and new velocities are tangential there, so the required first impulse is prograde, with

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