Answer: 0.25 seconds.
Step-by-step explanation:
The yo-yo does 240 revolutions in one minute, and we know that one minute has 60 seconds, then the revolutions per second can be calculated as:
240 rev/60s = 4 rev/s, this will be the frequency of the yo-yo
The frequency is actually written as: f = 4 Hz = 4 s^-1
We want to find the period of this yo-yo.
The period is the duration of one cycle, and we have the relation:
f = 1/T
Where f is the frequency and T is the period, then:
T = 1/f
And we know the value of f, it is f = 4 s^-1
Then the period will be:
T = 1/(4 s^-1) = (1/4) s
Then the period of the yo-yo is 1/4 seconds = 0.25 seconds.