A body of mass 0.4 kg is tied to one end of a string and the other end of the string is tied to a small pivot on a vertical wall . Calculate the minimum speed of the body required at its lower most pint to avoid slacking of string at any point in its motion along the vertical circle of radius 1 m .

Explanation

To solve the problem, we need to determine the minimum speed of the body at its lowest point to ensure that the string remains taut throughout the vertical circular motion.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Mass of the body, \( m = 0.4 \, \text{kg} \) (not directly needed for speed calculation)
- Radius of the vertical circle, \( r = 1 \, \text{m} \)
- Acceleration due to gravity, \( g = 9.8 \, \text{m/s}^2 \)
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