1. Shrieking Rod Prof. Chih-Ta Chia Dept. of Physics NTNU

2. Problem # 13  Shrieking rod  A metal rod is held between two fingers and hit. Investigate how the sound produced depends on the position of holding and hitting the rod?

3. Vibration in rod?  How did you create vibrations in the rod?  Three type of vibrations are created simply by hitting the rod: Longitudinal, torsional and flexural vibrations.  Longitudinal and Flexural vibrations are most likely to last longer, but not the torsional vibrations.  What are the resonance conditions for these three vibrations?  What are the speeds of these three vibrations that travel in the rod. How to determine the wave velocity?

4. Vibration of Rod?  What is the damping effect on the longitudinal and vibrations? Hitting position dependence? Time dependence?  Longitudinal wave damping and flexural vibration damping? Which one is damped fast?

5. Cylindrical Rod : Longitudinal and Torsional wave Longitudinal wave speed E: Young’s Modulus Torsional wave speed  : Shear Modulus Passion Ratio :

6. Young’s Modulus Stress: S Longitudinal Strain: S t Young’s Modulus: E

7. Hook’s Law Stress is proportional to Strain. Stress, Strain and Hook’s Law

8. Shear Modulus The shear modulus is the elastic modulus we use for the deformation which takes place when a force is applied parallel to one face of the object while the opposite face is held fixed by another equal force. Shear Modulus: 

9. Resonance : When Clamped in the Middle

10. Speed of wave in Rod

11. Flexural Vibrations Equation of Motion : (Length L and radius a) c l is the velocity of longitudinal waves in an infinitely long bar. The radius of gyration  is defined as above. For the circular rod,  is half the bar’s radius. As for the square rod,  is D/√12.