A conical pendulum can be constructed by attaching one end of a string to some type of overhead support such as a door frame, ceiling, or other support. Then the other end of the string is attached to a reasonably dense object that will not be extensively impacted by air resistance. Set the object into circular motion by giving it a push tangent to the circle to establish horizontal circular motion. This may take a few practice runs to perfect.

Without spinning the conical pendulum, pull the object out so that the string makes your selected angle (20*) with the vertical. Use the spring scale to measure the horizontal outward force required to keep the object at this angle.