Chapter 8 Angular Kinetics

Question 1

What is Moment of inertia?

Answer 1

1) the inertial property of a rotating body

2) represents the resistance to angular acceleration

3) both mass and the distance the mass is distributed from axis of rotation affects the moment of inertia

Question 2

How do you calculate moment of inertia?

Answer 2

Sum of the product of each particles mass and the radius of rotation for that particle squared

I = summation mr^2

Question 3

What is radius of gyration?

Answer 3

it is the distance from the axis of rotation (joints) to the body’s mass (foot)

Question 4

How does knee angles affect moment of inertia?

Answer 4

the changes of the radius of gyration for the lower leg and foot with respect to the hip changes everything your move your legs

Question 5

What is muscular Strength?

Answer 5

Ability of produce a torque at a joint

Question 6

What is segmental moment of interia?

Answer 6

resistance to rotation at a joint

Question 7

What is angular momentum?

Answer 7

1) quantity of angular motion a body possess

2)
calculated as the product of moment of inertia by angular velocity

H = I * ω
or
H = mk^2 * ω

Question 8

What are the 2 components of angular momentum?

Answer 8

1) Local term

2) Remote term

Question 9

What is Local term?

Answer 9

The local term is based on the segment’s angular momentum about its own segmental CG

Question 10

What is remote term?

Answer 10

remote term represents the segment’s angular momentum about the total-body CG

Question 11

What is the principle of conservation of angular momentum?

Answer 11

The total angular momentum of a given system remains constant in the absence of external torques

H1 = H2

or

(mk^2ω)1 =(mk^2ω)2

Question 12

When angular momentum is the same, what is the trade off between moment of inertia and angular velocity?

Answer 12

1) large angular velocity, low moment of inertia

2) small angular velocity, Large moment of inertia

Question 13

What is angular impulse?

Answer 13

The product of torque by the time interval over which the torque acts

angular impulse = torque x time = change in angular momentum

or

angular impulse = (moment of inertia 1 * angular velocity 1) - (moment of inertia 2 * angular velocity 2)

Question 14

What are the angular equivalents of mass, force, momentum and impulse?

Answer 14

1) Mass = moment of inertia

2) Force = Torque

3) momentum = angular momentum

4) impulse = angular impulse

Question 15

What is the angular analogues of Newton’s law of motion?

Answer 15

1) rotating body will maintain state of rest or constant motion unless acted on by external torque that changes state

2) net toque causes angular acceleration of magnitude equal to the torque , in the direction of torque and is inversely proportional to body’s moment of inertia

T = moment of inertia *
angular acceleration

or

T = mass * radius of gyration ^ 2 * angular acceleration

3) For every angular action, there is an equal and opposite angular reaction

Question 16

What is Centripetal Force?

Answer 16

it is the force directed towards the center of rotation for a body in rotational motion