At the three vertices of an equilateral triangle of side \(a\), three point charges are placed (each of \(0.1\,\text{C}\)). If this system is supplied energy at the rate of \(1\,\text{kW}\), calculate the time required to move one of the charges to the mid-point of the line joining the other two. 
Two charges, \( q_1 = +3 \, \mu C \) and \( q_2 = -4 \, \mu C \), are placed 20 cm apart. Calculate the force between the charges.