Revisiting Newton’s Law: Torques Creating Rotations

What is torque?

Torque is a moment

It is a force that has a tendency to rotate an object about a fixed axis

Angular: Newton’s 1st Law

Object’s resistance to change. To remain in a static state unless acted upon by an external force

Rotating uniformly — not moving OR spinning around in the same direction at the same rate, unless external torque is present

What is moment of inertia?

Name given to rotational inertia, the resistance of any physical object to change it’s angular state of motion

Instead of quantifying mass for inertia, we use mass and axis of rotation

Moment of inertia = Rotational inertia = I

What is radius of gyration?

Linear distance from where masses are centered on system and axis of rotation

• We want to know where the position of COG is

• Symbol for radius of gyr = k