Grade 12 Physics - Circular Motion - Universal Gravitation

[synchrostarr]

Homework Statement

This question is from the Nelson Grade 12 Physics textbook.

The force of attraction between masses m₁ and m₂ is 26N in magnitude. What will the magnitude of the force become if m₂
is tripled, and the distance between m₂ and m₁ is halved?

Homework Equations

F_G=(Gm₁m₂)/r²

G=6.67x10^-11

The Attempt at a Solution

I tried to look at both equations, the original and the altered equation so I had:

26N=(Gm₁m₂)/r²

and then for the changed equation I had"

F_G=(Gm₁3m₂)/(1/2)(r²)

But I was unable to figure out what to do from there.

If it is at all helpful, the answers in the back of my textbook said that the correct answer is 3.1x10²N.

 

[gneill]

Homework Statement

This question is from the Nelson Grade 12 Physics textbook.

The force of attraction between masses m₁ and m₂ is 26N in magnitude. What will the magnitude of the force become if m₂
is tripled, and the distance between m₂ and m₁ is halved?

Homework Equations

F_G=(Gm₁m₂)/r²

G=6.67x10^-11

The Attempt at a Solution

I tried to look at both equations, the original and the altered equation so I had:

26N=(Gm₁m₂)/r²

and then for the changed equation I had"

F_G=(Gm₁3m₂)/(1/2)(r²)

But I was unable to figure out what to do from there.

If it is at all helpful, the answers in the back of my textbook said that the correct answer is 3.1x10²N.

Hi synchrostarr, Welcome to Physics Forums.

You're on the right track. Note that if you halve the distance then the "1/2" applies to r, not to r².

After you insert the changes into the formula, see if you can't factor them out so you end up with something like:

F_new = C x (Gm₁m₂)/r²