Two indentical balls, each having a charge of `2.00xx10^(-7) C` and a mass of 100g , are suspended from a common point by two insulating strings each 50 cm long. The balls are held at a separation 5.0cm apart and then released. Find (a) the electric force on one of the charged balls (b) the components of the resultant force on it along and perpendicular to the string (c) the tension is the string (d) the acceleration of one of the balls. Answers are to be obtained just after the release.

Explanation

` Q_1=Q_2=2xx10^-7C, `
` M=100gm `
` l=50cm=50xx10^-2m, `
` D=5xx10^-2m `
(a) Now electric force
` F=K(Q_1Q_2)/D^2 `
` =14.4Nxx10^-2N=0.144N `
(b) The components of resultant force along it is Z,because mg balances T costheta.
` also, F=mg=Tsintheta `
` (c) Tansion of the string `
` Tsintheta=F `
` Tcostheta=mg `
` T^2=F^2+(mg)^2 `
` =(0.144)^2+(0.1xx9.8)^2 `
` i.e. T=0.986N.`