One end of string of length 1.5 m is tied to a stone of mass 0.4 kg and the other end to a small pivot on a smooth vertical board. What is the minimum speed of the stone required at its lowermost.point so that the string does not slack at any point in its motion along the vertical circle ?

Explanation

To solve the problem of finding the minimum speed of the stone at its lowermost point so that the string does not slack at any point in its vertical circular motion, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Forces at Play**:
At the lowest point of the circular motion, the stone experiences two forces: the gravitational force acting downwards (weight of the stone) and the tension in the string acting upwards. For the string to remain taut, the tension must be greater than zero.

2. **Identify the Required Conditions**:
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