% Circular orbit: use km and seconds consistently
Re_km = 6378;
mu_km3_s2 = 398600.4418;
h_km = 500;

r_km = Re_km + h_km;
v_km_s = sqrt(mu_km3_s2 / r_km);
T_s = 2*pi*sqrt(r_km^3 / mu_km3_s2);

fprintf('Radius: %.1f km\n', r_km)
fprintf('Speed: %.3f km/s\n', v_km_s)
fprintf('Period: %.2f min\n', T_s/60)