Rule:
Quantity that varies = k·
>>...The force of attraction between two bodies varies...<<
That's the quantity that varies. We'll call it F. That goes on
the left of the equal sign.
>>...directly with the product of their masses...<<
So the two masses go on top on the right of the equal sign. We
will call them m1 and m2.
>>...and inversely with the square of the distance between them...<<
That's the inversely. We'll call it d². It goes on the bottom on the
right. So we have:
F = k·
That's the incomplete formula. We must find k before we have the
complete formula:
>>...The force of attraction is 6 pounds when masses of 64 slugs and 108 slugs are 24 feet apart.<<
We substitute F=6, m1=64, m2=108, d=24
6 = k·
6 = k·12
= k
0.5 = k
Now we have k. Now we substitute 0.5 for k in this:
F = k·
F = 0.5·
And that is the complete formula. Now that we have the complete
formula, we are ready to use it. Here is what we are to use it to
find:
>>..Find the force of attraction when two masses are 25 slugs each and 60 feet apart..<<
We substitute m1 = 25, m2 = 25, d = 60
F = 0.5·
F = 0.5·
F = 0.5·
F = 0.5·
F = ·
F = 25/288 = .0868 pounds.
Edwin