find the acceleration due to gravity in a mine of depth 640 m if the value at the surfaceis 9.800 ms^-2`. The rdius of the earth is 6400 km.

Explanation

To find the acceleration due to gravity in a mine of depth 640 m, we can use the formula for gravity at a depth below the Earth's surface:

\[ g' = g \left(1 - \frac{d}{R}\right) \]

Where:
- \( g' \) = acceleration due to gravity at depth
- \( g \) = acceleration due to gravity at the surface (9.8 m/s²)
- \( d \) = depth of the mine (640 m)
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