Answer:
a. 5 Hertz
b. 35 rotations
Step-by-step explanation:
a. Frequency is given by
where
is the period, in seconds. Given that
, the frequency of this object's rotation is:

b. Since one rotation, or period, is completed in 0.2 seconds, divide the amount of time (7 seconds) by the time it takes to complete one revolution (0.2 seconds):
