Posted by Jennifer on .
A stone is tied to a string (length = 0.450 m) and whirled in a circle at the same constant speed in two different ways. First, the circle is horizontal and the string is nearly parallel to the ground. Next, the circle is vertical. In the vertical case the maximum tension in the string is 18.0% larger than the tension that exists when the circle is horizontal. Determine the speed of the stone.

Physics 
bobpursley,
in the vertical, tension at the bottom is mg+mv^2/r
In the horizontal, tension is mv^2/r
1.18 mv^2/r=mg+mv^2/r
solve for v 
Physics 
Jennifer,
How do u know the mass?

Physics 
bobpursley,
Mass does not matter. Notice mass divides out. divide both sides of the equation by m.

Physics 
Adam,
What did u you get as the answer.. i have a feeling mine is wrong

Physics 
Adam,
I can't divide out the v's and I know you are solving for "v".. but I can't seem to finish it out..
I got...
8.1v^2=mg+mv^2/r Then
8.1v^2=g + v^2/.45
then I don't know what to do from there