Electrostatics and Coulombines: Diagram Included.

AI Thread Summary
Two small spheres, each with a mass of 0.1g, are suspended and repel each other, resting 24cm apart after being given equal charges. The charge on each sphere is calculated to be approximately 6.86 x 10^-8 coulombs using Coulomb's law and the weight of the spheres. A discussion arose regarding the use of distance in calculations, clarifying that the full distance between the spheres should be used rather than half. The importance of understanding the forces acting on the spheres and their equal magnitudes was emphasized. The participant also sought additional resources for similar problems and shared a graphic to illustrate their understanding.
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Homework Statement


2 small spheres each having a mass of 0.1g are suspended from the same point on silk threads 20cm long. When given equal charges, they repel, resting 24cm apart. Calculate charge of each.


Homework Equations


F(w)=mg(a)
F=kQ(1)Q(2)/d^2
k=8.987x10^9 N*m^2 / c^2

The Attempt at a Solution


I converted grams to kilograms.. 1 x 10^-4 kg
kilograms to Newtons/weight..9.8*10^-4N

blah blah..
F=kQ(1)Q(2)/d^2
(7.35*10^-4N)(.24^2)(8.987*10^9 N*m^2/c^2)=Q^2
Q=6.86*10^-8C

http://i80.photobucket.com/albums/j199/pugfug90/physucks.gif
Here's some work and a diagram. I am 99% sure that the answer is 6.9*10^-8 coulombs. However! I don't understand.. If I used trig to find half of the total force (in the triangle diagram).. why do I use the full distance?
 
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If I understand what you're asking: You aren't finding just half the force. Coulomb's law obeys Newton's third law, so the force exerted on Q1 by Q2 has to have the same magnitude as the force of Q2 on Q1, it is just in the opposite direction.
 
AHHHHHHH

But mah physical teacher drew this line between both balls (for notes) and labeled it force.. Hage, that kind of makes sense. Thanks for help. So force isn't really "half", therefore just because I'm using "half force" doesn't mean I use half distance..?

Anyone want to do the problem, starting with..

"2 small spheres each having a mass of 0.1g are suspended from the same point on silk threads 20cm long. When given equal charges, they repel, resting 24cm apart. Calculate charge of each."

Also, any online links with similar problems?
----
coulaw.gif

http://i80.photobucket.com/albums/j199/pugfug90/physicismean.gif
Because of that image, and a nice guy that kind of explained it.. I made this graphic and I hope it shows that I understand:) What do you guys think of it?
 
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Hey hey can anyone confirm my work of art?
 
heyheyheyheyhey
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

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I was thinking using 2 purple mattress samples, and taping them together, I do want other ideas though, the main guidelines are; Must have a volume LESS than 1600 cubic centimeters, and CAN'T exceed 25 cm in ANY direction. Must be LESS than 1 kg. NO parachutes. NO glue or Tape can touch the egg. MUST be able to take egg out in less than 1 minute. Grade A large eggs will be used.
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