Alpha particles which have a charge +2e and mass 6.64 ✕ 10−27 kg are initially at rest and are fired directly at a stationary lead nucleus (charge +82e) at a speed of 1.95 ✕ 107 m/s. determine the distance of closest approach (in fm) before the alpha particle reverses direction. assume the lead nucleus remains stationary. assume the alpha particles are initially very far from a stationary lead nucleus.