Answer:
 t = 0.1111 s
Explanation:
Let's reduce the magnitudes to the SI system
  d = 120 mm (1m / 1000 mm)
  d= 0.120 m
  w = 540 rpm (2pi rad / 1 rev) (1 min / 60s) Â
   w= 56.55 rad / s
When at maximum speed we can use angular kinematic relationships to find the time for a sperm revolution with zero angular acceleration
   W = θ / t
   t = θ / w
   t = 2π / 56.55
   t = 0.1111 s