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The first & second stage of two stage rocketseparately weigh 100 kg and 10 kg and contain800kg and 90kg fuel respectively. If the exhaustvelocity of gases is 2 km/sec then velocity ofrocket after second stage is (nearly)(log, 5=0.6990) (neglect gravity)1) 7.8 x 10 m/s 2) 9.3 x 10 m/s3) 2.4 x 10 m/s4) 6.1 x 10 m/s |
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Answer» Answer: The answer is 7.82 X 10^3 m/s. Explanation: The initial VELOCITY of the rocket V0 = 0 Velocity of the rocket after exhaustion of the forst stage is V = μ ln m0 / m Here, m0 = 100 + 10 + 800 +90 = 1000 KG m = 100 + 10 + 90 = 200 Kg Thus |V| = 2 ln 5 = 2 x 1.609 = 3.218 Km/s The second stage becomes operative when the first is DETACHED from it. μ0 = 3.218 Km/s m0 = 10 + 90 = 100 Kg m = 10 Kg Thus, |V| = 3.22 + 2ln (100 /10) = 3.22 + 2 X (2.3) = 7.82 X 10^3 m/s |
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