What minimum horizontal speed should be given to the bob of a simple pendulum of length l so tht it describes a complete circle?

Explanation

To find the minimum horizontal speed that should be given to the bob of a simple pendulum of length \( l \) so that it describes a complete circle, we can follow these steps:

### Step 1: Understand the Problem
We need to determine the minimum speed \( u \) at the lowest point of the pendulum such that the bob can complete a vertical circular motion. The critical point occurs when the bob is at the top of the circle.

### Step 2: Analyze Forces at the Top of the Circle
At the top of the circular path, the forces acting on the bob are:
- The gravitational force \( mg \) acting downwards.
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