Show that this equation is inverse square

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    Inverse Square
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Homework Help Overview

The discussion revolves around the equation F = k(Q2*Q1)/(r^2), which is identified as an inverse square law. Participants are exploring the relationship between the force F and the distance r, particularly how changes in r affect F while keeping the charges Q1 and Q2 constant.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to understand the concept of inverse square by plugging in various values for Q1, Q2, and r. There is confusion regarding what is meant by "inverse" and how the squared distance affects the force.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the concept of inverse square. Some guidance has been provided regarding fixing the values of Q1 and Q2 while varying r, but there is still uncertainty about the implications of this relationship.

Contextual Notes

Participants express a need for simpler explanations and clarification on the roles of the variables in the equation, particularly the constancy of Q1 and Q2 compared to the variability of r.

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Homework Statement


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

Homework Equations

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.

Any advice is appreciated.
 
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This function is dependent on the inverse squared of r, which is usually the distance between the locations of Q1 and Q2.
 
brycenrg said:

Homework Statement


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

Homework Equations

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.

Any advice is appreciated.
What RUber said . ...

So, pick values for Q1 and Q2 and stay with those. Then plug-in various values for r.
 
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SammyS said:
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 said:
Yes. That is exactly what "inverse square" means. Google is your friend; see
https://en.wikipedia.org/wiki/Inverse-square_law
Thank you, Yeah i googled it but thought the Q's changed as well. So it didn't make sense. Sometimes i need someone to explain it to me like I am 5.
 
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