Answer
$1.8\;Hz$
Work Step by Step
Period $T=0.56\;s$
The relation between frequency and the period is
$f=\frac{1}{T}$
Plug the value of $T$.
$f=\frac{1}{0.56\;s}$
We can write $\frac{1}{s}=Hz$.
$f=\frac{1}{0.56}Hz$
Rounded value.
$f=1.8\;Hz$.
