n elastic balls are placed at rest on a smooth horizontal plane which is circular at the ends with radius
r as shown in the figure. The masses of the balls are
m,m2,m22,...,m2n−1 respectively. What is the minimum velocity which should be imparted to the first ball of mass
m such that this
nth ball will complete the vertical circle ?
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/960666/original_36.png)