Universal Gravitation Practice

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Homework Statement

What force does Earth exert on a 80.0-kg astronaut at an altitude equivalent to 2.5 times Earth's radius?

Homework Equations

F_G = (Gm₁m₂) / r²
Radius of Earth: 6370 km
Mass of Earth: 5.97x10²⁴ kg

The Attempt at a Solution

F_G = (Gm₁m₂) / r²
F_G = (G x M_Earth x 80 kg) / (6370 x 2.5)²
F_G = 2.00x10¹² N

The correct answer is 64 N

 

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What is G? And altitude means "above the surface of the Earth" and r means the distance from the centre of Earth.

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