how to find the gravitational field strength from the earth when no mass is given only distance(200km, 2000km and 50km)?

Question

beth12345 · Answer

the answer I'm given for the 200 km distance is 9.2N/kg, I was told to use $$F= G \times \left[\begin{matrix}m _{1} \times m _{2} /\ r ^{2}  \end{matrix}\right]$$ for the equation but I don't understand what the$$m _{1}$$and$$m _{2}$$are for, I am also not given the answer for the other distances

anonymous · Answer

since you know the force at distance 200Km so put it into the newton's gravitational force and calculate $$m_1\times m_2$$ then to find out the force between m1 and m2 you just need distance nothing else...

beth12345 · Answer

do you know what the $$m _{1}$$ and $$m_{2}$$ stand for?

anonymous · Answer

mass of the two particles which is under our consideration, i.e., between which we are finding the force.

beth12345 · Answer

what about if i'm not given the force or the mass of the 2000km and 50km distances?

anonymous · Answer

since $$F=G [m_1   \times m_2]/{r^2}$$ and you know G & $$m_1 \times m_2$$ 

then when you put r=2000Km then you get force between m1 and m2 at distance 2000km.

beth12345 · Answer

thanks, I got it now :)

anonymous · Answer

welcome.