A circular paper plate, a ruler, a string to measure diameter of the plate and online ruler if you do not have handy ruler, a napkin, cell phone as stopwatch, calculator. Steps: Take a circular paper plate. If you do not have it, then cut a circular shaped paper from a newspaper or cereal box or packing box or from any stiff paper object. Mark a point on it as a starting point. Now take a napkin and hold it on your hand in a way that you are ready to wipe that plate in a circular motion. Now rotate your hand with napkin in circular motion from the start point with a constant speed 10 times. When you begin rotating your hand start as 3, 2, 1 and go. At go, start stopwatch from your phone to record time for 10 rotations. This time is t (seconds). If it comes in minutes from stopwatch, change it to seconds. Now find time period, T = t/10 in seconds. Now measure the diameter of the plate in cm and change it to the meters. Now find its radius, r = d/2 in meters where d is diameter in meters. Now find