Physics problem on force of a charge

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SUMMARY

The discussion centers on calculating the electrostatic force between two point charges, specifically q1 = +10nC and q2 = -18nC, positioned on the x-axis. The correct formula to use is Coulomb's law, represented as f = (k * |q1 * q2|) / r², where k = 9.0 x 10^9 N m²/C². The initial calculation was incorrect due to a misunderstanding of unit conversion and the application of the formula, leading to an erroneous result of 1.3122 x 10^14 N.

PREREQUISITES
  • Coulomb's law for electrostatic force calculations
  • Understanding of charge units, specifically nanocoulombs (nC)
  • Basic algebra for manipulating equations
  • Knowledge of vector direction in force calculations
NEXT STEPS
  • Review the concept of Coulomb's law and its applications in electrostatics
  • Learn about unit conversions, particularly for electrical charge
  • Practice calculating forces between multiple point charges
  • Explore the concept of electric field and its relation to force
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Students studying physics, particularly those focusing on electrostatics, as well as educators looking for examples of charge interactions and force calculations.

Joshua Beyer
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Homework Statement


Two point charges are on the x-axis. One charge, q1 = +10nC, is located at the origin, and the other charge, p2=-18nC is located at x = 9.0m

Homework Equations


a.) what is the force on q2(include direction)?
b.) what is the force on q1(include direction)?

The Attempt at a Solution


f=(k(q1q2)/r^2)
f=(9.0*10^9(10*18)/9^2)
K = coulomb's law = 9.0*10^9
I got 1.3122*10^14, but was told that was WAY wrong.
 
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HI, Joshua. Welcome to PF!

(1) Note that the charge is given in units of nC. You need to take into account the "n".
It's a very good idea to include units in your calculation and make sure that the units combine to give the correct unit for the force.

(2) Looks like you multiplied by 9^2 rather than divided by 9^2.

(3) "k" is Coulomb's constant, not Coulomb's law.
 
Joshua Beyer said:

Homework Statement


Two point charges are on the x-axis. One charge, q1 = +10nC, is located at the origin, and the other charge, p2=-18nC is located at x = 9.0m

Homework Equations


a.) what is the force on q2(include direction)?
b.) what is the force on q1(include direction)?

The Attempt at a Solution


f=(k(q1q2)/r^2)
f=(9.0*10^9(10*18)/9^2)
K = coulomb's law = 9.0*10^9
I got 1.3122*10^14, but was told that was WAY wrong.

I believe the "n" in "nC" stands for "nano".
 

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