The primary disturbing force due to inertia of reciprocating parts of mass m at radius r moving with an angular velocity \[\omega \] is given by:

• A. \[m{{\omega }^{2}}r\sin \theta \]
• B. \[m{{\omega }^{2}}r\cos \theta \]
• C. \[m{{\omega }^{2}}r\frac{\sin 2\theta }{n}\]
• D. \[m{{\omega }^{2}}r\frac{\cos 2\theta }{n}\]