Answer
(a) $10.1\mu m$
(b) $64m/s$
Work Step by Step
(a) We can determine the maximum amplitude as follows:
$F_{max}=m\omega^2 A$
$\implies F_{max}=m(2\pi f)^2A$
$\implies F_{max}=4\pi ^2mf^2 A$
This can be rearranged as:
$A=\frac{F_{max}}{4\pi^2mf^2}$
We plug in the known values to obtian:
$A=\frac{40000N}{4\pi^2(0.10\times 10^{-3}Kg)(1.0\times 10^6Hz)^2}$
This simplifies to:
$A=10.1\mu m$
(b) The maximum speed of the disk can be determined as
$v_{max}=2\pi fA$
We plug in the known values to obtain:
$v_{max}=2\pi (1.0\times 10^6Hz)(10.1\times 10^{-6}m)$
$\implies v_{max}=64m/s$