Alpha particles (mass = 6.7 X 10-27 kg, charge = + 2e) are shot directly at a gold foil target. We can model the gold nucleus as a uniform sphere of charge and assume that the gold does not move.
(a) If the radius of the gold nucleus is 5.6 X 10-15 m, what minimum speed do the alpha particles need when they are far away to reach the surface of the gold nucleus? (Ignore relativistic effects.)
(b) Give good physical reasons why we can ignore the effects of the orbital electrons when the alpha particle is (i) outside the electron orbits and (ii) inside the electron orbits.