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JEE Main20208 Jan 2020Evening ShiftPhysicsGravitationActual

An asteroid is moving directly towards the centre of the earth. When at a distance of 10 R ( R is the radius of the earth) from the centre of the earth, it has a speed of 12 km s - 1 . Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is 11.2 k m s - 1 ) ? Give your answer to the nearest integer in km s - 1 ___

Correct answer

0

Step-by-step solution

K E i + P E i = K E f + P E f 1 2 m u 0 2 + - G M m 10 R = 1 2 m v 2 + - G M m R v 2 = u 0 2 + 2 G M R 1 - 1 10 v = u 0 2 + 9 5 G M R = 12 2 + 9 5 11.2 2 2 = 144 + 0.9 11.2 2 = 156.896 = 16.028   km   s - 1 ≃ 16   km   s - 1

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