Notes

Moment of inertia

\[ I = \int r^2 dm \] \[ I=I_{com} + Mh^2 \]

Common formulae

Rotational Inertia through central axis of hoop

\[ I = MR^2 \]

RI through central axis of an annular cylinder

\[ I = \frac{1}{2}M(R_1^2+R_2^2) \]

Solid cylinder about central axis

\[ I = \frac{1}{2}MR^2 \]

Solid cylinder about central diameter

\[ I = \frac{1}{2}MR^2 + \frac{1}{12}ML^2 \]

Thin rod about central diameter

\[ I = \frac{1}{12}ML^2 \]

Solid cylinder about diameter

\[ I = \frac{2}{5}MR^2 \]

Thin spherical shell about any diameter

\[ I = \frac{2}{3}MR^2 \]

Hoop about diameter

\[ I = \frac{1}{2}MR^2 \]

Slab about center

\[ I = \frac{1}{12}M(l^2 + w^2) \]

Newton’s second law for rotation

\[ \tau_{net} =I\alpha \]

Work and rotational kinetic energy

\[ W = \int_{\theta_i}^{\theta_f} \tau \dd{\theta} \]

if \(\tau\) is constant, its just

\[ W=\tau(\theta_f-\theta_i) \]

\[ P=\tau \omega \]