What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?

What is the minimum velocity with which a body of mass m must enter a

1.	What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?
Answer» `SQRT(3gR)` `sqrt(5gR)` `sqrt(GR)` `sqrt(2gR)` ANSWER :B