Electrostatic Force/Coulomb's Law

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mattdsaun
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Homework Statement



Diagram of two point charges on a line: q1 = -5.15 nC at the left with point B 10.0 cm to its left, and q2 = -14.0 nC at the right with point A 10.0 cm to its left, 25.0 cm apart. Below are three answer fields for net electric field at A and B and electric force on a proton at A.


Homework Equations



F=qE

The Attempt at a Solution



So in solving the problem, parts a) and b) were rather easy, and I believed part c) would be easy as well. I assumed:

F=10156*(1.6E-19) which came out to 1.63E-15, but that was apparently incorrect and I'm not sure what else to try. Any help is really appreciated.
 
mattdsaun said:

Homework Statement



Diagram of two point charges on a line: q1 = -5.15 nC at 10.0 cm left of point A, q2 = -14.0 nC at 10.0 cm right of A, with B 10.0 cm left of q1 and 25.0 cm between q1 and q2. Followed by three answer fields for parts (a) to (c).


Homework Equations



F=qE

The Attempt at a Solution



So in solving the problem, parts a) and b) were rather easy, and I believed part c) would be easy as well. I assumed:

F=10156*(1.6E-19) which came out to 1.63E-15, but that was apparently incorrect and I'm not sure what else to try. Any help is really appreciated.

Welcome to PhysicsForums!


You are doing it correctly. So there are three possibilities:

i) there is a mistake in the online answer checker,

ii) you just punched in the wrong values by mistake when you did your multiplication (easy to check!)

iii) or there is a mistake in the online answer checker for part A and the E field there is actually incorrect.


It seems to me that the most likely is i).
 
nrqed said:
Welcome to PhysicsForums!


You are doing it correctly. So there are three possibilities:

i) there is a mistake in the online answer checker,

ii) you just punched in the wrong values by mistake when you did your multiplication (easy to check!)

iii) or there is a mistake in the online answer checker for part A and the E field there is actually incorrect.


It seems to me that the most likely is i).

Thanks for the reply. I wasn't aware that the problem had limited attempts and since posting this I have run out of attempts unfortunately. I have emailed my professor to ask him what was wrong with it and hopefully it'll get fixed. Thanks for the quick response!
 
10156 is not the same as the 10516 I saw in post 1. So the most likely is ii. Easy to check that 1.6*1.05 is not 1.63 but 1.68 indeed.

Pity about the score, but perhaps you have learned something much more valuable...
 
BvU said:
10156 is not the same as the 10516 I saw in post 1. So the most likely is ii. Easy to check that 1.6*1.05 is not 1.63 but 1.68 indeed.

Pity about the score, but perhaps you have learned something much more valuable...

Honestly did not even notice that, thanks for the help. That's what it was.