Consider two identical metallic spheres of radius \( R \) each having charge \( Q \) and mass \( m \). Their centers have an initial separation of \( 4R \). Both the spheres are given an initial speed of \( u \) towards each other. The minimum value of \( u_0 \), so that they can just touch each other is:
\( \text{( Take } k = \dfrac{1}{4\pi \varepsilon_0} \text{ and assume } kQ^2 > G m^2 \text{ where } G \text{ is the Gravitational constant )} \)
