Mike was running at a higher speed than Mitchell
At time
seconds, the mass has angular speed

and hence linear speed

After 8 s, its linear speed is

and has centripetal acceleration with magnitude

To maintain this linear speed, by Newton's second law the required centripetal force should have magnitude

I think the answer is (C.) but im not sure
B.earth rotates on its axis in 24 hours; i.e., it rotates 15° of longitude per hour.
In phase would mean both waves are at a positive peak, out of phase would mean one is at a positive whilst the other is at a negative. Out of phase would mean the waves cancel each other out