Consider a conical pendulum consisting of a bob of mass m revolving without friction in a circle at a constant speed v on a string of length L at an angle of θ from the vertical.
There are two forces acting on the bob:
the tension T in the string, which is exerted along the line of the string and acts toward the point of suspension.
the downward bob weight mg, where m is the mass of the bob and g is the local gravitational acceleration.
The force exerted by the string can be resolved into a horizontal component, T sin(θ), toward the center of the circle, and a vertical component, T cos(θ), in the upward direction. From Newton's second law, the horizontal component of the tension in the string gives the bob a centripetal acceleration toward the center of the circle:
T sin heta = frac {mv^2}{r} ,