A bob is attached to one end of weightless string and makes a vertical circle while looping . If the velocity of the bob at the lowest point is `70 " m s"^(-1)` then calculate the radius of the greatest possible loop .

Explanation

To solve the problem of finding the radius of the greatest possible loop for a bob attached to a weightless string, we can follow these steps:

### Step 1: Understand the scenario
The bob is moving in a vertical circle, and we are given the velocity of the bob at the lowest point (70 m/s). We need to find the maximum radius of the loop.

### Step 2: Apply the concept of centripetal force
At the highest point of the loop, the forces acting on the bob are its weight (mg) and the tension in the string (T). The centripetal force required to keep the bob moving in a circle is provided by the tension and the weight of the bob.

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