Term
What is moment of inertia? 

Definition
•the inertial property for rotating bodies
• represents resistance to angular acceleration
• based on both mass and the distance the mass is distributed from the axis of rotation



Term
____is the sum of the products of each particle’s mass (m) and the radius of rotation (r) for that particle squared. I = Smr2 

Definition


Term
what is the radius of gyration? 

Definition
•distance from the axis of rotation to a point where the body’s mass could be concentrated without altering its rotational characteristics
• used as the index for mass distribution for calculating moment of inertia:
I = mk2 


Term
Knee angle affects the moment of inertia of the swinging leg with respect to the hip because of changes in the 

Definition
radius of gyration for the lower leg and foot. 


Term
what is angular momentum? 

Definition
•quantity of angular motion possessed by a body
• measured as the product of moment of inertia and angular velocity:
H = Iw
H = mk2w 


Term
What is the principle of conservation of angular momentum? 

Definition
The total angular momentum of a given system remains constant in the absence of external torques.
H1 = H2
(mk2w)1 = (mk2w)2 


Term
When angular momentum is conserved, there is a tradeoff between 

Definition
moment of inerta and angular velocity 


Term
What produces change in angular momentum? 

Definition
angular impulse  the product of torque and the time interval over which the torque acts:
T t = DH
T t = (Iw)2  (Iw)1 


Term
What are the angular equivalents of linear kinematic quantities? 

Definition
Linear Angular
mass (m) moment of inertia (I = mk2)
force (F) torque (T = Fd )
momentum (M=mv) angular momentum (H=mk2w)
impulse (Ft) angular impulse (Fd t) 


Term
What is the angular law of inertia? 

Definition
A rotating body will maintain a state of rest or constant rotational motion unless acted on by an external torque that changes the state 


Term
What is the angular law of acceleration? 

Definition
A net torque causes angular acceleration of a body that is:
• of a magnitude proportional to the torque
• in the direction of the torque
• and inversely proportional to the body’s moment of inertia 


Term
What is the angular law of acceleration 

Definition


Term
What is the angular law of reaction? 

Definition
• For every angular action, there is an equal and opposite angular reaction.
• When one body exerts a torque on a second, the second body exerts a reaction torque that is equal in magnitude and opposite in direction on the first body. 


Term
What is centripetal force?


Definition
(force directed toward the center of rotation for a body in rotational motion)
mv2
Fc = r
Fc = mrw2 

