Question Detail
Question
The escape velocity from the surface of the Moon, given g_moon = g_E/5 and R_moon = R_E/4, is:
Correct Answer
Option C is the correct answer.
Detailed Explanation
Escape velocity v_e = √(2gR). For Earth, v_E = √(2g_E R_E) = 11.2 km/s. For the Moon, v_M = √(2(g_E/5)(R_E/4)) = √( (2g_E R_E) / 20 ) = √( (v_E)² / 20 ) = v_E / √20 ≈ 11.2 / 4.47 ≈ 2.5 km/s. The closest option is 2.8 km/s, which matches the result from the lecture's exercise.
Hint
v_e is proportional to the square root of g and R.