1. The problem statement, all variables and given/known data A runner jogs around a circular track 160 ft in diameter, what is the magnitude of the displacement vector when the runner has completed 1/4 of a lap? 1/2 a lap? What is the direction of the runner's displacement vector at 1/4 and 1/2 a lap? What is the magnitude of the runners displacement vector when a full lap is completed? 3. The attempt at a solution Ok, I am pretty much clueless on this, even after spending an hour reading my text book. (I'm -really- bad at physics). I calculated the circumference of the track to be 502 ft which makes 1/4 of the track 125.5 ft. But the online software said that the magnitude of 1/4 of a lap should be 113 ft. How did they get this number. Also the magnitude of a complete lap is obviously 0 ft, but I'm not sure how to go about solving for the directions either. Any help would be appreciated, like I said, I'm pretty clueless XD.