Definition: Angular Velocity

The period $T$ of an object moving in a circle is the time it takes to travel the full circle. Angular velocity (in radians) is given by $$\omega = \frac{2\pi}{T}.$$ Velocity can be found by writing distance travelled in a period as circumference, $2\pi r$, so $$v = \frac{2\pi r}{T} = \frac{2\pi}{T}r = \omega r.$$

Definition: Newton's Law of Gravitation

The gravitational force between two objects $m_1$ and $m_2$ is equal to $$F=\frac{Gm_1m_2}{r^2}$$The gravitational force is always attractive.

Definition: Apparent Weight

The normal force $N$ is also called the apparent weight because it is what you "feel" on your feet.