# Show that this equation is inverse square

## Homework Statement

F = k(Q2*Q1)/(r^2)

## The Attempt at a Solution

I asked my teacher and he said that this is an inverse square law. Didn't say anything else. He also mentioned k is constant.

I assume i can plug in random values and see if there is a pattern... k=1 for all
Set 1, q1 = 2, q2 = 4, r = 5
F1 = 8/25
Set 2, q1 = 1 q2 = 5, r = 4
F2 = 5/16
I plugged in random values but i don't really get it.
What is inverse of what? I see that the r is squared and its below the kq1q2. I'm stuck.

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RUber
Homework Helper
This function is dependent on the inverse squared of r, which is usually the distance between the locations of Q1 and Q2.

SammyS
Staff Emeritus
Homework Helper
Gold Member

## Homework Statement

F = k(Q2*Q1)/(r^2)

## The Attempt at a Solution

I asked my teacher and he said that this is an inverse square law. Didn't say anything else. He also mentioned k is constant.

I assume i can plug in random values and see if there is a pattern... k=1 for all
Set 1, q1 = 2, q2 = 4, r = 5
F1 = 8/25
Set 2, q1 = 1 q2 = 5, r = 4
F2 = 5/16
I plugged in random values but i don't really get it.
What is inverse of what? I see that the r is squared and its below the kq1q2. I'm stuck.

What RUber said . ...

So, pick values for Q1 and Q2 and stay with those. Then plug-in various values for r.

• brycenrg
What RUber said . ...

So, pick values for Q1 and Q2 and stay with those. Then plug-in various values for r.
Thank you so, r is the only value that is changing?

Ray Vickson
• 