Circumference is 2*pi*r = 2*3.14*39 = 244.92 m. 5 trips means 5*244.92 = 1,244.6 m. A radian is 2*pi, therefore, he makes 10pi radians in 220 seconds. Or pi/22 radians/sec is his angular speed. His linear speed is the distance he travelled (1,244.6 m) divided by 220 seconds, which is approximately 5.657 meters per second.