Posted by Stephanie on .
A 3.1 kg ball is tied to a string and swung in a horizontal circle at a speed of 7.2 m/s. the radius of the circle is 2.2 m.
What angle does the string make with the horizontal?
What is the tension in the string?

Physics 
ajayb,
Assume the string makes an angle theta with the horizontal and tension in the string is T.
T*Cos theta = m*v^2/r (centrifugal force)
and T*Sin theta = m*g
By dividing: Tan theta = g*r/v^2
= 9.8*2.2/7.2^2
= 0.41
So Theta = 22.5 deg
Now T=m*g/Sin22.5 = 79.3N