Angular kinetics review
Download
1 / 21

Angular Kinetics Review - PowerPoint PPT Presentation


  • 277 Views
  • Updated On :

Angular Kinetics Review . Source: Chapter 12 of Basic Biomechanics by Susan Hall Reference to figures in this presentation refer to the former text by Kreighbaum, which is on reserve. Torque and Motion Relationships. Relationship between linear and angular motion

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Angular Kinetics Review' - brilliant


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Angular kinetics review l.jpg
Angular Kinetics Review

  • Source: Chapter 12 of Basic Biomechanics by Susan Hall

  • Reference to figures in this presentation refer to the former text by Kreighbaum, which is on reserve


Torque and motion relationships l.jpg
Torque and Motion Relationships

  • Relationship between linear and angular motion

    • displacement, velocity, and acceleration (Fig H.1, p 315)

  • Angular analogue of Newton’s third law (F=ma), the instantaneous effect of a force or torque

    • Torque = moment of inertia (I) X angular acc ( (Fig H.5-H.7)

      • What is torque?

      • What is moment of inertia ?(Fig H.3, p 319)

      • What is radius of gyration (Fig H.4, p 320)

      • Changing moment of inertia and radius of gyration in the body (Figures H.8 and H.9, p 323 and 324)

      • Calculations using a 3-segment system

      • Homework problem




Instantaneous effect of net torque torque is constant l.jpg
Instantaneous effect of net torque: Torque is constant Constant

What is rotational inertia,

Or moment of inertia?



What is moment of inertia l.jpg
What is Moment of Inertia? Constant

It is the resistance of a system to rotational acceleration, and is

calculated at follows:

Here, r (the radius of rotation) is equal to k (the radius

of gyration), but that is not the case with extended bodies


What is radius of gyration k l.jpg
What is radius of gyration (k)? Constant

k

35

An indicator of distribution of mass

about the axis. It is the distance from

the axis to a point at which all the

mass of a system of equal mass

would be concentrated to have the

MOI equal the original system. It

is, then, the average weighted

distance of the mass of a system

to the axis.

Equivalent systems

k

35


Determining moi k l.jpg
Determining MOI & K Constant

  • Simple 3-segment system:

    • I = 3mi di2 = m1 d12 + m2 d22+

      m3 d32 + . . . . . . .+ mi di2

    • I = mk2 ; k = (I/m).5

  • Irregularly shaped bodies

But we can’t measure all of these small masses!


Physical pendulum method of determining moi and k l.jpg
Physical pendulum method of determining MOI and K Constant

  • Suspend object at axis

  • Measure mass (m), and distance from axis to COM, r

  • Measure period of oscillation (T)

    • Moment of inertia (I) = T2 mr * .248387 m/sec

    • Radius of gyration (K) = ( I/m).5



Changing i and k in the human body l.jpg
Changing ConstantIandk in the human body


Changing i and k in the human body13 l.jpg
Changing ConstantIand k in the human body



Angular momentum l.jpg
Angular Momentum positions

  • Impulse-momentum relationship - effect of force or torque applied over time

    • Linear: Ft = mv Rotational: Tt = I 

  • What is angular impulse? (Fig I.1, I.2, I.3, p 327-8)

    • Torque X time

  • What is angular momentum? (Fig I.4, p 329)

    • amount of angular movement: I 

  • Conservation of angular momentum (Fig I.4, I.5, I.6 p 329-331)

    • Angular momentum is constant if net impulse is zero








ad