☆彡Get a stone (small size), an empty ball pen tube, and a string (you can also use yarn). let the other end of the string pass through the empty ball pen tube and to the other end, attach a stone. Hold the ball pen tube with your hand and whirl it so that it moves in horizontal circle. Make the ball pen tube rotate in a circle with a smaller radius, then a bigger radius after a minute. Observe and com- pare the speeds at different radii. Is a force necessary to keep an object in circular motion? What keeps the object in a circular orbit?​