A body falls from infinity to Earth's surface. Its velocity at the surface (in terms of escape velocity v_e):
Av_e/2
B2 v_e
Cv_e
D√2 v_e
Answer & Solution
Correct answer: C. v_e
By energy conservation: (1/2)mv² - 0 = 0 - (-GMm/R), so v = √(2GM/R) = v_e. The escape velocity equals the impact velocity from infinity (by time-reversal symmetry).
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