How Do Key Swings Maintain a Circular Path?

[farhannaeem]

Keys with a combined mass of 0.100 kg are attached to a 0.25m long string and swung in a circle in the vertical plane.
a) What is the slowest speed that the keys can swing and still maintain a circular path?
b) What is the tension in the string at the bottom of the circle?

 

[praharmitra]

Show what you have done and where you are stuck.

 

[farhannaeem]

i don't know how to approach it like how to start the problem

 

[tiny-tim]

start by writing out all the equations you know that might help

(if you don't know any, go back to your book or your lecture notes and find some)