The Squeaky Aluminum Rod February 22, 2K+1 by Dick Heckathorn for C.V.C.A. Physics

Frequency Meter Program Apparatus 1.829 meter 3/8 Aluminum Rod Rosin Apple ][e Computer Frequency Meter Program Tape Recorder + Cable

Record the frequency and where held. Investigate Holding Rod at Center Create a Frequency What is the frequency? Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______

What do you think ‘f’ will be? Record the frequency and where held. Investigate Hold Rod 1/4 From One End What do you think ‘f’ will be? Create the Frequency Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______ 2 1/4 _______

What do you think ‘f’ will be? Record the frequency and where held. Investigate Hold Rod 1/6 From One End What do you think ‘f’ will be? Create the Frequency Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______ 2 1/4 _______ 3 1/6 _______

What do you think ‘f’ will be? Record the frequency and where held. Investigate Hold Rod 1/8 From One End What do you think ‘f’ will be? Create the Frequency Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______ 2 1/4 _______ 3 1/6 _______ 4 1/8 _______

What do you think ‘f’ will be? Record the frequency and where held. Investigate Hold Rod 1/10 From One End What do you think ‘f’ will be? Create the Frequency Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______ 2 1/4 _______ 3 1/6 _______ 4 1/8 _______ 5 1/10 _______

What do you think ‘f’ will be? Record the frequency and where held. Investigate Hold Rod 1/12 From One End What do you think ‘f’ will be? Create the Frequency Record the frequency and where held.

Trial Location Frequency (Hertz) 1 1/2 _______ 2 1/4 _______ 3 1/6 _______ 4 1/8 _______ 5 1/10 _______ 6 1/12 _______

It increased in whole number multiples of the original frequency. Question? What relationship exists as the position where the rod changed from 1/2 to 1/4 to 1/6 to 1/8 etc. It increased in whole number multiples of the original frequency.

Trial Location Frequency (Hertz) 1 1/2 ____ 2 1/4 ____ 3 1/6 ____ 4 1/8 ____ 5 1/10 ____ 6 1/12 ____

What is the wavelength of the fundamental frequency? Question? What is the wavelength of the fundamental frequency? The fundamental frequency is ______

What pattern might we look for? What about node and antinode regions? Question? Is there a wave pattern? What pattern might we look for? What about node and antinode regions?

Hold rod at center - Create ‘f’ An antinode at either end. Investigate Hold rod at center - Create ‘f’ Grab hold of rod at various locations. What was found? A node at the center. An antinode at either end.

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A

The rod is ___ wavelength long. A N A The rod is ___ wavelength long. L = 1/2   = 2 L  = 3.66 m

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66

Hold rod at 1/4 - Create ‘f’ An antinode at either end and... Investigate Hold rod at 1/4 - Create ‘f’ Grab hold of rod at various locations. What was found? A node 1/4 from either end. An antinode at either end and...

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A N A

The rod is ___ wavelength long. A N A N A The rod is ___ wavelength long. L =   = L  = 1.83 m

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66 2 1/4 ____ 1.83

Hold rod at 1/6 - Create ‘f’ An antinode at ________. Investigate Hold rod at 1/6 - Create ‘f’ Grab hold of rod at various locations. What was found? A node at ____________. An antinode at ________.

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A N A N A

The rod is ___ wavelength long. A N A N A N A The rod is ___ wavelength long. L = 3/2   = 2/3 L  = 1.22 m

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66 2 1/4 ____ 1.83 3 1/6 ____ 1.22

Hold rod at 1/8 - Create ‘f’ Investigate Hold rod at 1/8 - Create ‘f’ Grab hold of rod at various locations. What was found? A node at _____________. An antinode at _________.

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A N A N A N A

The rod is ___ wavelength long. A N A N A N A N A The rod is ___ wavelength long. L = 4/2   = 2/4 L  = 0.91 m

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66 2 1/4 ____ 1.83 3 1/6 ____ 1.22 4 1/8 ____ 0.91

Hold rod at 1/10 - Create ‘f’ Investigate Hold rod at 1/10 - Create ‘f’ Grab hold of rod at various locations. What was found? A node at _____________. An antinode at _________.

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A N A N A N A N A

The rod is ___ wavelength long. A N A N A N A N A N A The rod is ___ wavelength long. L = 5/2   = 2/5 L  = 0.73 m

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66 2 1/4 ____ 1.83 3 1/6 ____ 1.22 4 1/8 ____ 0.91 5 1/10 ____ 0.73

Hold rod at 1/12 - Create ‘f’ An antinode at either end. Investigate Hold rod at 1/12 - Create ‘f’ Grab hold of rod at various locations. What was found? A node at the center. An antinode at either end.

Place a ‘N’ for node location. Describe Pattern Rod Place a ‘N’ for node location. Place an ‘A’ for antinode location. A N A N A N A N A N A N A

The rod is ___ wavelength long. A N A N A N A N A N A N A The rod is ___ wavelength long. L = 6/2   = 2/6 L  = 0.61

Trial Location f  (Hertz) (m) 1 1/2 ____ 3.66 2 1/4 ____ 1.83 3 1/6 ____ 1.22 4 1/8 ____ 0.91 5 1/10 ____ 0.73 6 1/12 ____ 0.61

A N A N A N A N A N A A N A A N A N A A N A N A N A A N A N A N A N A A N A N A N A N A N A N A

Trial Location f  v (Hertz) (m) (m/s) 1 1/2 ____ 3.66 ____ 2 1/4 ____ 1.83 ____ 3 1/6 ____ 1.22 ____ 4 1/8 ____ 0.91 ____ 5 1/10 ____ 0.73 ____ 6 1/12 ____ 0.61 ____

frequencies is the same. What if this were not the case? Conclusion The velocity of all frequencies is the same. What if this were not the case?

Summary When we examined the rod to determine the location of nodes and antinodes, we found:

The rod is ___ wavelength long. 1/2 A N A The rod is ___ wavelength long. L = 1/2   = 2 L  = 3.66 m

The rod is ___ wavelength long. 1/4 A N A N A The rod is ___ wavelength long. L =   = L  = 1.83 m

The rod is ___ wavelength long. 1/6 A N A N A N A The rod is ___ wavelength long. L = 3/2   = 2/3 L  = 1.22 m

The rod is ___ wavelength long. 1/8 A N A N A N A N A The rod is ___ wavelength long. L = 4/2   = 2/4 L  = 0.91 m

The rod is ___ wavelength long. 1/10 A N A N A N A N A N A The rod is ___ wavelength long. L = 5/2   = 2/5 L  = 0.73 m

The rod is ___ wavelength long. 1/12 A N A N A N A N A N A N A The rod is ___ wavelength long. L = 6/2   = 2/6 L  = 0.61

1/2  1/4  1/6  1/8  1/10  1/12  A N A N A N A N A N A A N A A N A N A N A N A N A N A