Final answer:
The mass of each pith ball can be calculated using the equation m = (k*q^2 / (l^2*g))*sin(θ).
Step-by-step explanation:
In equilibrium, the tension in each string is equal and opposite to the electric force between the pith balls. Therefore, we can write the equation:
T*sin(θ) = k*q^2 / l^2
where T is the tension in the string, θ is the angle between the strings, k is the electrostatic constant, q is the charge on each pith ball, and l is the length of the string.
From this equation, we can find the relationship between the mass of each ball m and the tension T:
T = m*g
where g is the acceleration due to gravity.
By substituting the value of T from the first equation into the second equation, we can solve for the mass of each ball:
m = (k*q^2 / (l^2*g))*sin(θ)