Ex. 31. Ex. 31. With what velocity should an a-particle travel towards the nucleus of a S atofn so as to arrive at a distance 10 metre from the nucleus of the Cu atom (Cu =29, e = 1-6 x 10 C, E = 8:85 x 10 JCmm, = 9-1 x 10 kg (IIT 1997 Solution: We have ZZe mp (13 4Tt Eg d Substituting Z, = 29, Z, = 2 and the given values in the above equatbot we get U = 5-41x 10 m/s.