Question

A planet has a mass of $8.4\times {10}^{24}kg$, which is about wight times the mass of its moon. If the distance between the planet and the moon is about $4.2\times {10}^{5}km$, what is the gravitational pull of the planet on the moon?

• A. $2.1\times {10}^{29}N$
• B. $3.3\times {10}^{21}N$
• C. $2.1\times {10}^{23}N$
• D. $3.3\times {10}^{27}N$

Answer 1

The correct option is D $3.3\times {10}^{27}N$

According to question......................

$\begin{array}{c}\Rightarrow Massoftheplanet{m}_1=8.4\times {10}^{24}kg\\ \Rightarrow Massofthemoon{m}_2=\frac{m_1}{8}=\left(\frac{1}{8}\right)8.4\times {10}^{24}kg\\ \Rightarrow Distancebetweentheplanetanditsmoonr=4.2\times {10}^{5}km\\ \Rightarrow GravitationalpulloftheplanetonthemoonF=\frac{G{m}_1{m}_2}{r^2}\\ \Rightarrow \frac{6.67259\times {10}^{-11}N{m}^2/k{g}^2\times 8.4\times {10}^{24}kg\times \left(\frac{1}{8}\right)8.4\times {10}^{24}kg}{{(4.2\times {10}^{5}km)}^2}\\ \therefore 3.33\times {10}^{27}N\end{array}$

the correct option is D.