Given:
(1) The mass of the planet (M) is eight times the mass of the earth, i.e., 8 × 6 × 1024 kg
(2) The radius of the planet (R) is twice the radius of the earth, i.e., 2 × 6.4 × 106 km
(3) G = 6.67 × 10-11 N·m2/kg2
Escape velocity for that planet
= 2.237 × 104 m/s
= 22.37 km/s