Posted by Rudy on .
Determine the tension in the string at the top and bottom of its path when a 0.3 kg yoyo is whirled in a vertical circle of radius 0.5 m at 2.5 m/s.
I'm sure I can solve this, I just can't find the equation for tension. The only equation I could find in my book is if something is in equilibrium.

Physics 
Marth,
Remember that tension is just a force. Therefore, it helps to draw a free body diagram.
There are two forces on the yoyo: the force of weight, and the tension of the string. Because the object is rotating, the tension results in a centripetal force (always directed inwards to the center of the circle).