SOLUTION: The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart. If two equally charged balls are placed 0.1m apart and the force be

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart. If two equally charged balls are placed 0.1m apart and the force be      Log On


   

Question 1178647: The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart. If two equally charged balls are placed 0.1m apart and the force between the balls is 9.8*10^-4 Newtons, calculate the charge on each ball to 2 significant figures, given K=9.0*10^9.
Found 2 solutions by mananth, ikleyn:
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart. If two equally charged balls are placed 0.1m apart and the force between the balls is 9.8*10^-4 Newtons, calculate the charge on each ball to 2 significant figures, given K=9.0*10^9.

F=K%2Aq1q2%2Fr%5E2+
r= 0.1
F= 9.8*10^-4 Newtons,
K=9.0*10^9.
q=?
F=K%2Aq1q2%2Fr%5E2+
F=K%2Aq%5E2%2Fr%5E2+
9.8%2A10%5E-4+=+%289.0%2A10%5E9%29+%2A%28+q%5E2%2F+0.1%5E2%29
q%5E2+=+%28%289.8%2A10%5E-4%29+%2A%280.1%5E2%29%29%2F+%289.0%2A10%5E9%29
+q%5E2+=+1.8+.10%5E-15
q= 3.5+%2A+10%5E-15



Answer by ikleyn(53614) About Me  (Show Source):
You can put this solution on YOUR website!
.
The formula F=Kq1q2/r^2 gives the force between two point charges of q1 and q2 coulombs that are r metres apart.
If two equally charged balls are placed 0.1m apart and the force between the balls is 9.8*10^-4 Newtons,
calculate the charge on each ball to 2 significant figures, given K=9.0*10^9.
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        Calculations in the post by @mananth are incorrect.
        I came to bring a correct solution. 


F = K%2A%28%28q1%2Aq2%29%2Fr%5E2%29

r = 0.1

F = 9.8*10^-4 Newtons,

K = 9.0*10^9.

q=?


    Substitute the values into the basic formula


9.8%2A10%5E%28-4%29 = %289.0%2A10%5E9%29+%2A%28q%5E2%2F+0.1%5E2%29

q%5E2 = %28%289.8%2A10%5E%28-4%29%29%2A%280.1%5E2%29%29%2F+%289.0%2A10%5E9%29

q%5E2 = %289.8%2F9.0%29%2A10%5E%28-15%29

q%5E2 = 1.0888+%2A+10%5E%28-15%29 = 10.888+%2A+10%5E%28-16%29

q = 3.23%2A10%5E%28-8%29     <<<---===  ANSWER

Solved.