Question

What α-particle energy would be necessary in order to explore the field of force within a radius of 10⁻¹² cm of the center of nucleus of atomic number 60, assuming classical mechanics to be adequate?

Answer 1

The minimum requirement is that the particle should be able to penetrate the nucleus of radius R. Thus 

T = 1.44z Z/R(fm) = 1.44 × 2 × 60/10 ≈ 17.3 MeV