$5.$ True or False: Critical speed is the velocity at which a rotating system's natural frequency matches its operating frequency.

$6.$ True or False: Influence coefficients are used to determine the exact weight and position of balancing masses without trial runs.

$7.$ True or False: V$-$engines require more complex balancing compared to inline engines due to their geometry.

$8.$ True or False: Graphical methods of balancing are outdated and no longer used in modern engineering.