Angular Kinetics ( Test 2 ) Flashcards
What is angular kinetics
the study of angular motion with regards to force
What is the angular analogue of mass
Moment of Inertia ( I )
What is the Moment of Inertia
It’s an objects resistance to angular acceleration
What are the two factors that influence ( I )
- m = the mass of the object
2. k = the distribution of mass, relative to the axis of rotation
What is k
The radius of gyration
How do we find ( I )
set up the object as a pendulum and time how long it takes to rotate
How does ( I ) affect rotation
the smaller the I the easier to rotate
Can one manipulate their I
yes, not by changing their mass, but by changing k. It can be done by bringing your arms in to decrease I, or sticking them out to increase I.
How many ( I )’s does an object have
3
- Anterior/Posterior
- Medial/Lateral
- Long axis
What is Newtons first law for angular kinetics
a rotating body will remain in a state of constant rotational motion unless acted upon by an outside torque. ( Conservation of Angular Momentum )
What is Angular momentum
H = Iω = mk²ω
In the absence of net external torque what is true about H (angular momentum)
It in conserved
When angular momentum is conserved, or there is not net torque acting on the object what do we know about I and ω
Not much, although H is constant I and ω can change.
What is needed for a change in angular momentum ( H )
torque and time
When thinking about momentum for a projectile, what happens to the center of mass trajectory.
It doesn’t change, it’s still subject to gravity
Although angular momentum is conserved while the body is airborne, can it be transfered from one segment to another.
Yep, but momentum for one segment will increase and the momentum for the other will decrease proportionally
Can one even change the direction of rotation while airborne
yep
What is newtons 2nd law for angular kinetics
Torque causes angular acceleration, ( and ∆H )
ΣT = I α
How can a person change Momentum ( H )
an external force
What is angular impulse
Torque over a period of time ( torque x time )
What is newtons 3rd law for angular kinetics
For every torque exerted by one body on another there is an equal ( in size ) and opposite ( in direction ) torque exerted on the second body by the first body.
Know the two tables under angular kinetics
ok
