Final answer:
The tension in the string at the bottom of the circle depends on the centripetal force.
Step-by-step explanation:
In order for an object to move in a vertical circular path, there must be a centripetal force acting towards the center of the circle. At the top of the circle, the centripetal force is the sum of the tension in the string and the gravitational force pulling the object downwards.
At the bottom of the circle, the centripetal force is the sum of the tension in the string and the gravitational force pulling the object upwards.
To find the tension in the string at the bottom of the circle, you can use the centripetal force equation:
T + mg = mv^2/r