- #1
chukie
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Two small pith balls, each of mass m = 12 g, are suspended by 1.2 m fine strings and are not moving. If the angle that each string makes with the vertical is q = 42.6 , and the charges on the two balls are equal, what is that charge (in microC)?
http://img386.imageshack.us/img386/5977/picmd8.th.jpg
I equated the forces in x and y to zero:
Tcos42.6-117.6=0
T=159.76
Tsin42.6+Fe=0
plugging in 159.76
Fe=108
then i used the equation Fe=kQ^2/r^2
i solved for r by doing this:
r=2(1.2sin42.6)
r=1.6 m
I'm not sure if my steps are right. Can someone help me? Thanks in advance!
http://img386.imageshack.us/img386/5977/picmd8.th.jpg
I equated the forces in x and y to zero:
Tcos42.6-117.6=0
T=159.76
Tsin42.6+Fe=0
plugging in 159.76
Fe=108
then i used the equation Fe=kQ^2/r^2
i solved for r by doing this:
r=2(1.2sin42.6)
r=1.6 m
I'm not sure if my steps are right. Can someone help me? Thanks in advance!
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