A bicycle starts at the origin of a circular track that has a circumference of 126 m and travels at a constant speed a distance s = 38.0 m in a time t = 12s.

a)what is the angular displacement (in rad) of the bicycle from its starting position? r=20.1 so theta or angular displacement is 38/20.1 = 1.89 rad

b) What is the centripetal acceleration (in m/s^2) of the bicycle? omega= dtheta/dt or 1.89 rad/12s = 0.158 rad/s
so centripetal acceleration is: rw^2 (w is omega) or 20.1(0.158)^2 = 0.50 m/s^2. Check me on that one.

C) What is the angular speed (rad/s) of the bicycle? angular speed or omega (w) is already determined to be 0.158 rad/s.

d) What is the orbital period of the bicycle, as it rounds the track?
T= 2pi/w (omega) >> 6.28/0.158 = 39.7s

Please review my work. I'm a bit uncertain.

all ok.