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Find the approximate percentage decrease in the weight of a rocket when it is taken to a height of 32 km above the Earth's surface. (Radius of the Earth = 6400 km.)

1. 1 %
2. 3%
3. 4%
4. 0.5%

Correct answer: 1 %

Solution

For h much less than R, g at height h is g(1 - 2h/R), so the fractional decrease in weight is 2h/R = 2*32/6400 = 64/6400 = 0.01 = 1%.

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