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

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

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

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

5. 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.

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

7. 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.

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

9. 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.

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

11. 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.

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

13. 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.

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

15. 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.

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

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

18. 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?

19. 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.

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

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

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

23. 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...

24. 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

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

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

27. 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 ________.

28. 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

29. 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

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

31. 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 _________.

32. 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

33. 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

34. 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

35. 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 _________.

36. 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

37. 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

38. 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

39. 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.

40. 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

41. 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

42. 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

43. 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

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

45. 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?

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

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

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

49. 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

50. 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

51. 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

52. 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

53. 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