1 / 14

Agenda

Agenda. Learn some new information. Finish Chicken Stretching Lab Plot your data. Answer Post-Lab Questions Discuss muscle hypertrophy and muscle atrophy. More about Young’s Modulus. Young’s modulus is a measure of the material’s resistance to deformation .

fred
Download Presentation

Agenda

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Agenda • Learn some new information. • Finish Chicken Stretching Lab • Plot your data. • Answer Post-Lab Questions • Discuss muscle hypertrophy and muscle atrophy.

  2. More about Young’s Modulus • Young’s modulus is a measure of the material’s resistance to deformation. • Young’s modulus quantifies how much stress is required to generate a give strain. • Independent of the size or shape of the object • Only depends the material the object is composed of. • Copper has a modulus of 120 x 109 Pa. • Steel has a modulus of 200 x 109 Pa. • Thus, steel is more resistant to deformation then is copper.

  3. Viscoelasticity • When an elastic material containing fluid is deformed the return of the material to it’s original shape is time delayed. • Viscoelastic materials exhibit both an elastic response and viscous damping. • Bones, tendons, ligaments, cartilage, muscle, and skin are all viscoelastic.

  4. Properties of a Viscoelastic Material • The mechanical response of a viscoelastic material are time and velocity dependent. • Viscoelastic materials exhibit: • a hysteresis • a creep response • a force relaxation response • Are time dependent, if the force is held for a longer time they exhibit greater hysteresis. • A velocity dependent, stiffness of the material increases with increasing velocity of loading.

  5. Hysteresis for a Viscoelastic Material

  6. Creep • Creep is a time dependent response of viscoelastic tissues. • The muscle-tendon complex is loaded with a weight. • When the load is initially applied the muscle undergoes deformation. Following this initial deformation the muscle continues to deform at a much lower rate, this later deformation is creep.

  7. Loading Tissues • Muscle tissue adapts to training, or application of an overload stress, by increasing cross-sectional area as individual fibers increase in diameter. • How many of you saw this occur during the lab?

  8. Graphing Your Data • Pull out your data from last class. • Sit with your partners. • Steps to Graphing: • Find domain and range of your data. • Determine the scale for each axis. • Label axes with values, titles and units. • Plot your points.

  9. Determine Domain and Range Domain Range Range: change iny-values. Look for your maximum y-value Stress will be your value Find the range for each sample: Range of Sample 1: Range of Sample 2: Which sample has the larger range? • Domain: change in x-values. • Look for your maximum x-value • Strain will be your x-value • Find the domain for each sample: • Domain of Sample 1: • Domain of Sample 2: • Which sample has the larger domain?

  10. Determine Scale X-axis Range Choose the larger range set. Find an incremental value that would be a good scale to go from the smallest value to the largest value: i.e. if your range is 0-200, a possible incremental value is 10 • Choose the larger domain set. • Find an incremental value that would be a good scale to go from the smallest value to the largest value: • i.e. if your domain is 0-50, a possible incremental value is 5 You want your increment to be small enough to capture your data, but large enough to fit on your graph.

  11. Label Axes X-Axis Y-Axis Using your incremental value, number your axis from 0 to just beyond your maximum range value. Label your axis: Stress Give units:Pa • Using your incremental value, number your axis from 0 to just beyond your maximum domain value. • Label your axis: Strain • Give units: N/A

  12. Plot Points • Plot each point. • Recommendation: Plot all of your Sample 1 points. • Highlight them one color using a marker. • THEN plot Sample 2 points. • Highlight them a different color. • Create a Key. • Note: You may have to estimate some of the points if they don’t fit exactly on the line.

  13. Calculations • Label elastic limit • Calculate Young’s Modulus **IF YOU CANNOT CALCULATE THE YOUNG’S MODULUS, PLEASE EXPLAIN A POSSIBLE SOURCE OF ERROR THAT YIELDED YOUR RESULTS***

  14. Post-Lab Questions • Think back to when you were testing the chicken, what did you observe happening to the chicken muscle as more mass was added to your sample? • Did you see creep occur while testing your chicken sample? Use your data to support your answer. • Explain why you saw the cross-sectional area of your sample increase as you added more weight. What is happening here? • Why do you think it is important to complete this lab? What information can we learn that can be applied to sports biomechanics?

More Related