Torque and Center of Mass Lecture Notes

A set of vocabulary flashcards based on lecture notes covering torque calculations, rigid bodies, and the definitions and locations of Center of Mass (CM) and Center of Gravity (CG).

Positive Torques

Torques that tend to produce an anti-clockwise rotation of an object.

Moment arm is zero

The condition occurring when the line of action of force passes through the axis of rotation (the hinge), resulting in a torque of $0\,Nm$.

Rigid body

A body that does not deform or change shape and is made of a large number of interconnected particles.

Center of mass (CM)

The point about which mass is equally distributed or considered concentrated.

Parabolic path

The smooth trajectory followed by the center of mass of a thrown hammer while other points travel along more complicated paths.

Weight

The force of gravity concentrated at the center of gravity.

Center of gravity (CG)

The point where the whole weight of the body appears to act.

CM/CG for tall objects

Refers to a slight difference in center of mass and center of gravity for objects like mountains and buildings because the value of acceleration due to gravity decreases with altitude.

Geometric center

The location of the CM/CG for a homogeneous cube or sphere.

Axis of symmetry

The line on which the CM/CG of a right circular cylinder or cone is located.

Mid-point

The location of the CM/CG of a uniform wooden rod, allowing it to be balanced from its center.