Answer:
a) Frequency = 10 Hz
b) Period, T = 0.025 s
Step-by-step explanation:
We know that period and frequency are reciprocal to each other.

a) An oscillating object takes 0.10 s to complete one cycle; that is, its period is 0.10 s, we need to find frequency
Period = 0.10 s

Frequency = 10 Hz
b) If the frequency is 40 Hz, what is the period T
Frequency = 40 Hz

Period, T = 0.025 s