A car driving along a highway at a speed of 22.9 m/s strays onto the shoulder. Evenly spaced parallel grooves called “rumble strips” are carved into the pavement of the shoulder. Rolling over the rumble strips causes the car’s wheels to oscillate up and down at a frequency of 87.0 Hz. How far apart are the centers of adjacent rumble-strip grooves?
m

Please provide explanation and answer.