Determine the first space velocity for a planet whose mass and radius is 2 times the mass and radius of the Earth.

The first cosmic speed V can be found as the speed at which the centripetal acceleration a is equal to the acceleration of gravity g.
g = F / m = (GmM / R²) / m = G * (M / R²), where G is the gravitational constant, m is the mass of the satellite, M is the mass of the planet, R is the radius of the planet.
a = V² / R, where V is the speed.
GM / R² = V² / R
GM / R = V²;
V = root (GM / R).
Let us express the speed in terms of values for the Earth:
V = root ((G * 2Mz) / 2Rz) = root (GMz / Rz);
V = root ((6.67 • 10-11 N * m² / kg² * 5.97 • 1024 kg) / 6 371 000 m) = 7906 m / s.
Answer: the first space velocity for the planet and the Earth is the same – 7906 m / s.