- #1
danielhep
- 14
- 1
Homework Statement
Two m = 4.0 g point charges on 1.0-m-long threads repel each other after being charged to q = 80 nC , as shown in the figure. What is the angle θ? You can assume that θ is a small angle.
Homework Equations
Fe=kq2/r2
F=ma
Fg=mg
The Attempt at a Solution
Equation 1:[/B]
r = 2sinθ
Fe=kq2/(2sinθ)2
Equation 2:
tanθ=Fe/Fg
Fgtanθ=Fe
Combining Them:
Fgtanθ=kq2/(2sinθ)2
Fgtanθ=kq2/(4(sinθ)2)
(sinθ)2tanθ=kq2/(4Fg)
(sinθ)2tanθ=kq2/(4mg)
Okay, so now I have an equation with all the thetas on one side. So I tried to plug it into Wolfram Alpha to solve for theta, but it is giving me some really weird results. I'm not quite sure where I went wrong. Any help is greatly appreciated! Here's the Wolfram Alpha link. Thanks!
http://www.wolframalpha.com/input/?...*(8*10^-9)^2/(4*4*10^-3*9.8)+for+x+in+degrees