 Solution

ID: past-exam-of-the-physics-1-paper-of-the-university-of-oxford/2013/11/d/solution

Setting

1/ r \to 0

in b gives the asymptotic speed

v_{\infty} = 2 2^{2} - \frac{2 ( 1.32712 \times 1 0 ^{11} )}{1.5 \times 1 0 ^{9}} ≃ 17.52 km s^{- 1} .

The radicand is positive, so the ideal probe has positive total mechanical energy and escapes the Sun. The later dust-cloud model takes this limiting speed as its initial speed.

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