Speed: The number of meters travelled per second. As we have already seen, speed is the distance travelled by the object per second. When the object is traveling in a circle, each trip around the circle adds 1 circumference worth of meters to the distance travelled. Using the stopwatch and the numbers on the grid, determine the speed of the ball as it goes around in the circle. Measure the radius of the circle to the middle of the ball. Work with care, but your will get a larger margin of allowable error in this part to compensate for your estimation of the circle's radius.