Question

Two equally charged insulating balls each weigh 0.42 g and hang from a common point by identical threads 35 cm long. The balls repel each other so that the separation between their centers is 6.4 cm. What is the magnitude of the charge on each ball?

I have tried using similar questions on here as a guideline and can't seem to get it

Answer 1

sinα =3.2/35 =0.091,
α=5.24⁰,
tanα=0.092.

T•sin α =F(el)=kq₁•q₂/r²=kq²/r²,
T•cosα=mg .
T•sin α/ T•cosα= kq²/r²mg,
tanα = kq²/r²mg,
q=sqrt{ r²•m•g•tan α/k}=
=sqrt{0.064²•0.00042•9.8•0.092/9•10⁹}=
=1.31•10⁻⁸ C .

Answer 2

thank you so much!