two identical pith balls,each carrying a charge q, are suspended from a common point by two strings of equal length ( L). FIND THE MASS OF EACH BALL.
if the angle between the string is 2theta in equilibrium ....
find the mass of each ball...
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Let m is the mass of each ball and balls are suspended from a common point by two strings of equal length L, at equilibrium condition angle between stings is 2θ as shown in figure.
at equilibrium ,
Tcosθ = mg
And , Tsinθ = Kq²/r² ,where r = 2Lsinθ
∴ Tsinθ/Tcosθ = Kq²/r²mg
⇒tanθ = Kq²/(2Lsinθ)²mg
⇒ m = kq²/{4L²sin²θ × tanθ × g}
= Kq²cosθ/4L²sin³θg
Hence, mass of each ball is kq²cosθ/4L²sin³θg
at equilibrium ,
Tcosθ = mg
And , Tsinθ = Kq²/r² ,where r = 2Lsinθ
∴ Tsinθ/Tcosθ = Kq²/r²mg
⇒tanθ = Kq²/(2Lsinθ)²mg
⇒ m = kq²/{4L²sin²θ × tanθ × g}
= Kq²cosθ/4L²sin³θg
Hence, mass of each ball is kq²cosθ/4L²sin³θg
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