Physics question: gravitation

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1

<p>i try to figure it out, but cannot. someone help plz</p>

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<p>answer is D, but why??</p>

<p>based on the equation U = - GMm/r, when objects are released, as the r decrease, G, M, m are constants. U approaches 0…</p>

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<p>No, U is initially zero and approaches negative infinity.</p>