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22 terms

Ch. 9, 10, and 11 Physics Vocab

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Axis
The straight line around which rotation takes place
Rotation
When an object turns about an internal axis, or spin
Revolution
When an object turns about an external axis
Linear Speed
The distance moved per unit of time
Tangential Speed
The speed of something moving along a circular path. The motion is always tangent to the circle
Rotational Speed
(Sometimes called angular speed) the number of rotations per unit of time
Centripetal Force
Any force that causes an object to follow a circular path
"Center seeking" or "towards the center"
Centrifugal Force
The outward force
"Center fleeing" or "away from the center"
Center of Gravity
Point at the center of an object's weight distribution, where the force of gravity can be considered to act.
Center of Mass
Often called center of gravity. The average position of all the particles of mass that make up an object
Unstable Equilibrium
The state of an object balanced so that any small displacement or rotation lowers its center of gravity
Stable Equilibrium
The state of an object balanced so that any small displacement or rotation raises its center of gravity
Neutral Equilibrium
The state of an object balanced so that nay small movement neither raises nor lowers its center of gravity
Lever Arm
The distance from the turning axis to the point of contact
Torque
The rotational analog of force; the product of a force and the lever arm (measured in newton meters). Tends to produce rotational acceleration.
Linear Momentum
Product of the mass and the velocity of an object. Also called momentum. (This definition applies at seeds much less than the speed of light.)
Angular Momentum
Product of rotational inertia and rotational velocity
Rotational Velocity
Rotational speed together with a direction for the axis of rotation or revolution
Law of Conservation of Angular Momentum
If no unbalanced external torques act on a rotation system, then the angular momentum of that system is constant.
Longitudinal Axis
The vertical axis that passes from head to toe. Rotational inertia about this axis is increased by extending a leg or arms.
Transverse Axis
When you perform a somersault or a flip. Tucking in your arms and legs reduces your rotational inertia about this axis. Straightening your arms and legs increase your rotational inertia about this axis.
Medial Axis
The front-to-back axis. You rate about this axis when doing a cartwheel.