The mass of Planet X is 4 times Earth's mass, and its radius is 2 times Earth's radius. What is the surface gravitational acceleration on Planet X compared to Earth's?
A2 × g_Earth
Bg_Earth (same)
C4 × g_Earth
D0.5 × g_Earth
Explanation
📌 Surface gravity g = GM/R². Ratio: g_X/g_E = (M_X/M_E) × (R_E/R_X)² = 4 × (1/2)² = 4 × 1/4 = 1. So g_X = g_Earth. Distractor A used mass factor alone; C ignored radius; D applied radius factor incorrectly (as 1/R without squaring).