Question 35694
We are given radius R=318m and t=1.8min . Since cyclist completes half round of the track in t minutes, the time needed to complete the whole track is T=2t=3.6min=216sec (this is the period of motion).
Angular velocity is ω=T2π , and velocity is a=ω2R . Thus, acceleration is a=T24π2R=0.27s2m .