A ` 5 MeV alpha ` particle is projected towards a stationary nucleus of atomic number 40. Calculate distance of closest approach.

Explanation

To calculate the distance of closest approach of a 5 MeV alpha particle projected towards a stationary nucleus with atomic number 40, we can follow these steps:

### Step 1: Understand the Concept
At the distance of closest approach, the kinetic energy of the alpha particle is equal to the electrostatic potential energy between the alpha particle and the nucleus.

### Step 2: Write the Formula
The potential energy (U) between two charged particles is given by:
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