16 Lab 1: Compressive Strength of Tissue

Acknowledgment

This project is made possible with funding by the Government of Ontario and through eCampusOntario’s support of the Virtual Learning Strategy. To learn more about the Virtual Learning Strategy visit: https://vls.ecampusontario.ca.

PHY255 Stay-At-home Experiment 1

Measuring the Ultimate Compressive Strength of the Biceps Muscle

What you will need:

• A smart phone installed with the Phyphox app
• Another device that is capable browsing internet through WiFi (such as a laptop, a tablet, or another smart phone)

Procedures:

1. In the Phyphox app, click on the “acceleration with g” sensor.
2. On the other device, use the web browser to remotely access (watch this video about how to start remote access) your Phyphox app.
3. Start a measurement of acceleration with g. Rotate the phone, and use the change in the acceleration to determine the correspondence between the directions of x/y/z in the data and the directions of height/width/thickness on the phone. Briefly describe how you determined the directions.
4. Clear the measurement above and start a new measurement. Rest your one of your upper arms on a flat surface. Keep the biceps of that arm relaxed. With the direction of height of the phone vertical and perpendicular to your biceps, strike your biceps with your phone gently. Leaving about 1 second between strikes, repeat the strikes 5~7 times with different forces. STOP increasing the force any further when you feel pain. Be careful and do not drop or damage your phone.
5. Stop the measurement above. Export the raw data for further analysis.
6. On the acceleration-time graph, determine the time points when (1) the phone touched on the skin; (2) the phone reaches the maximum depth into the muscle; and (3) the phone is bounced back due to the elasticity of the muscle.
7. Search online for the mass, the width, and the thickness of your cell phone. Using the acceleration-time graph to determine the following quantities for each strike: (1) the speed of the phone before hitting the skin; (2) the interaction time between the phone and the muscle; (3) the maximum compression depth of the muscle under the impact of the phone; (4) the maximum force applied by the phone on the muscle; (5) the maximum compressive stress applied by the phone on the muscle.
8. Repeat the steps 4~7 above with your biceps contracting.

Requirements of the experimental report:

• Font size: 12
• Line spacing: 1.5
• Only write these sections: Results, Discussions, and Suggestions of improvement.
• Total marks: 20/20
• Results (12/20):
  • Complete all the calculations that are required in the procedures above.
  • Show sample calculations.
  • Attach graphs or tables when necessary.
  • If you write a program for calculations, attach the code in the appendix.
• Discussions (8/20):
  • Find the uncertainty values for each of the calculation in your results section.
  • Identify the sources of error in your measurements.
  • Feel free to do more tests to verify your claims if possible.
  • Make a reasonable conclusion based on your results.
  • Compare your results with literature values (and add citations).
• Suggestions of improvement (+2 bonus; total marks capped at 20/20):
  • What other quantities can be determined with the same experimental design?
  • What can be done to reduce the uncertainties at no cost while staying at home?
  • Did you enjoy this experiment? What are the aspects that you dislike the most about this experiment?
• No page limit. But please try to be straightforward and concise! (Yuchong has a minor reading deficiency.)
• Join the classmates on the course discussion board!
  • Ask specific questions related to experimental procedures or calculations. (Remember to thank the student who helped you the most!)
  • If you understand the issue, try to answer the questions from other students without directly instructing them what to do.
  • The student who helped others the most (judging by the number of “thanks”) will be awarded with +1 bonus! (total marks capped at 20/20)