Question

v2/r=g ye formula kha se he . kis article se .​

Answer 1

It is from Vertical Circular Motion.

This the minimum value of centripetal or radial acceleration.

At the topmost point of VCM.

min. centripetal force = mg

therefore, (mv²)/r = mg

hence, v²/r=g

Hope It helped You!

edit: For example, consider a pendulum being whirled in a vertical circle.

the forces on the bob at the top most point: Mg and Tenstion(T)

so, F(cp) = Mg + T

so min.F(cp) = Mg

because there may be a situation when the tension on the string may become zero... but the weight of the bob cannot disappear.

I suggest you analyse the situation when a car moves on a overhead bridge and is at its topmost point too.