Answer
(a) $0.022s,45Hz$
(b) $1400rpm$
Work Step by Step
(a) We can find the time period and frequency as follows:
$f=(2700\frac{rev}{min})(\frac{1min}{60s})$
$f=45Hz$
Now $T=\frac{1}{f}$
$\implies T=\frac{1}{45}=0.022s$
(b) The required rpms can be determined as
$f=\frac{1}{T}$
$f=\frac{1}{0.044}\times \frac{60s}{min}$
$f=1400rpm$