$1.$ True or False: Dynamic balancing is necessary only for machinery that operates at high speeds.

$2.$ True or False: Static balancing is adequate for machinery that operates in multiple planes.

$3.$ True or False: A rotor's critical speed is the speed at which it naturally tends to rotate.

$4.$ True or False: Influence coefficients are only useful in theoretical analyses and are not used in practical balancing applications.