You may have seen in a circus a motorcyclist driving in vertical loops inside a death well (a hollow spherical chamber with holes, so the spectators can watch from outside). Explain clearly why the motorcyclist does not drop down when he is at the uppermost point of death well with no support from below. What is the minimum speed required at the uppermost position to perform a vertical loop if the radius of the chamber is 25 m ?

Explanation

To solve the problem, we will break it down into two parts:

1. **Explanation of why the motorcyclist does not drop down at the uppermost point of the death well.**
2. **Calculation of the minimum speed required at the uppermost position to perform a vertical loop with a radius of 25 m.**

### Part 1: Explanation

At the uppermost point of the vertical loop, the motorcyclist experiences two forces:
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