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JEE Mains · Physics · STD 11 - 7. gravitation

Two stars of masses \(3\times10^{31}\, kg\) each, and at distance \(2\times10^{11}\, m\) rotate in a plane about their common centre of mass \(O. A\) meteorite passes through \(O\) moving perpendicular to the star’s rotation plane. In order to escape from the gravitational field of this double star, the minimum speed that meteorite should have at \(O\) is : (Take Gravitational constant \(G = 6.67\times10^{-11}\, Nm^2\, kg^{-2}\))

  1. A \(2.4\times10^4\, m/s\)
  2. B \(1.4\times10^5\, m/s\)
  3. C \(3.8\times10^4\, m/s\)
  4. D \(2.8\times10^5\, m/s\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(2.8\times10^5\, m/s\)

Step-by-step Solution

Detailed explanation

\(\frac{1}{2}m{v^2} + \frac{{2\left( { - GMm} \right)}}{r} = 0\) \({V^2} = \frac{{4GM}}{r} = \frac{{4 \times 6.67 \times {{10}^{ - 11}} \times 3 \times {{10}^{31}}}}{{2 \times {{10}^{11}}}}\) \(V = 20\sqrt 2 \times {10^4}\,m/s\) \( = 2.828 \times {10^5}\,m/s\)
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