**Torque:**

The rotational/circular version of force.

Describes the point and angle that a force is applied, like opening a door is easier when perpendicular and when you apply a larger force on it.

AKA Turning effectiveness

Unit: Newton Meters

Technically a vector cross product and “r” and “F” are the magnitudes.

R = Distance from the center of mass from where the force is applied

F = Force applied

Theta = Angle on the point

**Rotational Inertia:**

The rotational/circular version of mass.

**Moment of Inertia:**

The sum of all inertias from every different point of mass of an object.

The one with the SMALLEST moment of inertia will move faster.

So if you roll things down a hill the one with most of its mass concentrated in the center will come down faster.

**Rotational Kinetic Energy:**

This can be added as an extra term for potential energy to turn into.

So if something is rolling down a ramp it starts with potential energy, which turns into both normal kinetic energy and rotational kinetic energy.

**Angular Momentum:**

**Conservation of Angular momentum:**

If inertia decreases, then velocity increases, that is why when ice skaters move their arms in they speed up.