Question # $4(15$ pts$)|$

An electric motor $($m $=100$kg$)$ is supported on elastomers $($k $=40$kN$/$m; $$c $=400$ Ns$/$m$).$ It is desired to $|$

limit the force transmitted to the foundation to $20\%$ of the force due to unbalance in the armature of the $|$

rotor. The unbalance force is known to be $(0\mathrm{.}2$w$?)$ N$.|$

$($a$)$ Determine and specify the minimum speed in RPM for the electric motor that must be maintained $|$

to satisfy the force transmission requirement. $(10$ pts$)|$

$($b$)$ What is the magnitude and phase of dynamic force transmitted to the foundation at this speed? $(5|$

pts$)|$