The value of acceleration due to gravity at Earth's surface is `9.8ms^(-2)`. The altitude (in metre) above its surface at which the acceleration due to gravity decreases to `4.9ms^(-2)`, is close to :(Radius of earth `=6.4xx10^(6)m`)

Explanation

To find the altitude above the Earth's surface where the acceleration due to gravity decreases to \(4.9 \, \text{m/s}^2\), we can use the formula for gravitational acceleration at a height \(h\) above the Earth's surface:

\[ g_h = \frac{G \cdot M}{(R + h)^2} \]

Where:
- \(g_h\) is the acceleration due to gravity at height \(h\),
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