(solution) Two insulating spheres have radii 0.300 cm and 0.500 cm, masses

(solution) Two insulating spheres have radii 0.300 cm and 0.500 cm, masses

Two insulating spheres have radii 0.300 cm and 0.500 cm, masses 0.400 kg and 0.700 kg, and uniformly distributed charges of -2.00 µC and 5.50 µC. They are released from rest when their centers are separated by 1.00 m.

(a) How fast will each be moving when they collide? (Hint: Consider conservation of energy and of linear momentum.) 

m/s (lighter sphere)

(b) If the spheres were conductors, would the speeds be greater or less than those calculated in part (a)? (Note: Assume a reference level of potential V = 0 at r = ?.)

m/s (heavier sphere)

Explain why please.