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Kris1120
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Homework Statement
Two small metallic spheres, each of mass
0.14 g are suspended as pendulums by light
strings from a common point as shown. The
spheres are given the same electric charge, and
it is found that the two come to equilibrium
when each string is at an angle of 7◦ with the
vertical.
The value of Coulomb’s constant is
8.98755 × 109 N · m2/C2 and the acceleration
of gravity is 9.81 m/s2 .
If each string is 13.7 cm long, find the mag-
nitude of the charge on each sphere.
Answer in units of nC.
Homework Equations
y=Tcos(theta)=mg
x=Tsin(theta)=Fe
The Attempt at a Solution
Tcos(7)=(.14g)(9.81)
T=1.38371
1.38371sin(7)=.168632
q=sqrt((.1683632)(2*(.137sin7)^2))/8.98755x10^9
q=1.44639e-7