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# Gravity watch

1. 1)The relationship between force and distance is proportional right? 1/r^2
(r is the distance) but why is it 1/r^2 and why is it proportional.

2) this formula

F= G m1m2/r^2

what does this formula want to show?

thanks
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3. (Original post by Lufthansa)
1)The relationship between force and distance is proportional right? 1/r^2
(r is the distance) but why is it 1/r^2 and why is it proportional.

2) this formula

F= G m1m2/r^2

what does this formula want to show?

thanks
Firstly 1/r^2 is an inversely proportional relationship meaning that as the distance increases, the force between the objects decreases at an increasing rate. It is inversely proportional because the masses of the two objects in question aren't going to change and G is a constant so the only unit we can change in this equation (for a specific set of objects) r and so by increasing r we in effect 1/r^2 x the original force and so the equation follows the above stated relationship.

Secondly the formula you stated shows the gravitational force between 2 objects (of masses m1 and m2) with usually one large mass (m1; for example the earth) and one small mass (m2; for example a satellite) and the question usually asks 'what is the gravitational force on the satellite?'.

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