Question

The masses of the earth and moon are $6\times {10}^{24}kg$ and $7.4\times {10}^{22}kg$, respectively. The distance between them is $3.84\times {10}^{5}m$. Calculate the gravitational force of attraction between the two. Use $G=6.67\times {10}^{-11}N{m}^{2}k{g}^{-2}$

• A. $1\times {10}^{26}N$
• B. $2\times {10}^{26}N$
• C. $3\times {10}^{26}N$
• D. $4\times {10}^{26}N$

Answer 1

The correct option is B $2\times {10}^{26}N$

From Newton's law of Gravitation,

$F=\frac{G{M}_1{M}_2}{r^2}$

where, $F$ is the force of attraction between earth and the moon, $M_1$ is the mass of the earth, $M_2$ is the mass of the moon and $r$ is the distance between the earth and the moon.

or, $F=\frac{(6.67\times {10}^{-11})(6\times {10}^{24})(7.4\times {10}^{22})}{(3.84\times {10}^5{)}^2}$

or, $F=2\times {10}^{26}N$