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Take the mean distance of the moon and
the sun from the earth to be 0.4\times10 ^{6} km
and 150 \times10 ^{6}  km respectively. Their
masses are 8 \times10 ^{22} kg and 2 \times10 ^{30} kg
respectively. The radius of the earth is
6400 km. Let \Delta F_{1} be the difference in the
forces exerted by the moon at the nearest
and farthest points on the earth and  \Delta F_{2}  be the difference in the force exerted by
the sun at the nearest and farthest points
on the earth. Then, the number closest to \frac{\Delta F_{1}}{\Delta F_{2}}  is :

Answers (1)

@Aravind gupta. watch this

https://www.youtube.com/watch?v=FVOVZOclDtU

\Delta f_{1}= \frac{-2GM_{e}m}{r_{1}^{3}} \Delta r1 \ \ and \ \ \Delta f_{2}=\frac{-2GM_{e}M_{s}}{r_{2}^{3}} \Delta r_{2}

\frac{\Delta f_{1}}{\Delta f_{2}} = \frac{m\Delta r}{r_{1}^{3}}\cdot \frac{r_{2}^{3}}{M_{s}\Delta r_{2}}=\frac{m}{M_{s}}\cdot \frac{r_{2}^{3}}{r_{1}^{3}}\cdot \frac{\Delta r_{1}}{\Delta r_{2}}

using \Delta r_{1} = \Delta r_{2} = 2 R_{earth} \ \ \ m=8\times 10^{22}kg, M_{s}=2\times 10^{30}kg

r_{1} = 0.4\times 10^{6}km, r_{2}=150\times 10^{6}km

we get \frac{\Delta f_{1}}{\Delta f_{2}}=2

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Safeer PP

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