Calculate the distance of closest approach when a proton of energy 3 MeV approaches a gold nucleus (Z=79).

Explanation

To calculate the distance of closest approach when a proton of energy 3 MeV approaches a gold nucleus (Z=79), we can follow these steps:

### Step 1: Understand the Problem
We have a proton with kinetic energy (KE) of 3 MeV approaching a gold nucleus. The gold nucleus has an atomic number Z = 79, which means it has 79 protons and therefore a charge of +79e.

### Step 2: Convert Energy to Joules
The energy of the proton is given in MeV. We need to convert this energy into joules for our calculations.
1 MeV = \(1.6 \times 10^{-13}\) Joules.
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