We describe a set of conceptual and hands-on activities based around understanding the dynamics of a Slinky that is hung vertically and released from rest. This Slinky drop experiment typically lasts a fraction of a second, but when observed in slow motion, one sees the Slinky compress from the top down while the bottom portion remains at rest—naively seeming to defy gravity—until the Slinky has completed its collapse. The motion, or lack thereof, of the bottom of the Slinky after the top is released sparks student curiosity by challenging expectations and provides motivation and context for learning about scientific model building.
References
1.
The bottom of the Slinky does not remain completely at rest, but it actually twists before the collapse completes. The torsional wave associated with this phenomenon moves much faster than the longitudinal wave and was explored as a final project by one group of students. https://www.youtube.com/watch?v=fbUmv5ok-so.
2.
M. G.
Calkin
, “Motion of a falling spring
,” Am. J. Phys.
61
, 261
–264
(March
1993
).3.
R.
Newburgh
and G. M.
Andes
, “Galileo redux or, how do nonrigid, extended bodies fall?
” Phys. Teach.
33
, 586
–588
(Dec
. 1995
).4.
M.
Graham
, “Analysis of Slinky levitation
,” Phys. Teach.
39
, 90
–91
(Feb
. 2001
).5.
M.
Sawicki
, “Static elongation of a suspended SlinkyTM
,” Phys. Teach.
40
, 276
–278
(May
2002
).6.
J. M.
Aguirregabiria
, A.
Hernandez
, and M.
Rivas
, “Falling elastic bars and springs
,” Am. J. Phys.
75
, 583
(July
2007
).7.
8.
R. C.
Cross
and M. S.
Wheatland
, “Modeling a falling slinky
,” Am. J. Phys.
80
, 1051
–1060
(Dec
. 2012
).9.
Varitasium YouTube Channel
, “Awesome hd slinky slow-mo
,” https://www.youtube.com/watch?v=uiyMuHuCFo4 (2012
).10.
B. F.
Albanna
, J. C.
Corbo
, D. R.
Dounas-Frazer
, A.
Little
, and A. M.
Zaniewski
, “Building classroom and organizational structure around positive cultural values
,” AIP Conf. Proc.
1513
, 7
–10
(2013
).11.
N.
Roth
, P.
Gandhi
, G.
Lee
, and J.
Corbo
, “The Compass Project: Charting a new course in physics education
,” Physics Today Online
, Points of View (Jan
. 8, 2013
).12.
D. R.
Dounas-Frazer
, J.
Lynn
, A. M.
Zaniewski
, and N.
Roth
, “Learning about non-Newtonian fluids in a student-driven classroom
,” Phys. Teach.
51
, 32
–34
(Jan
. 2013
).13.
D. R.
Dounas-Frazer
, G. Z.
Iwata
, and P. R.
Gandhi
, “Uncertainty analysis for a simple thermal expansion experiment
,” Am. J. Phys.
81
, 338
–342
(May
2013
).14.
P. R.
Gandhi
, J. A.
Livezey
, A. M.
Zaniewski
, D. L.
Reinholz
, and D. R.
Dounas-Frazer
, “Attending to experimental physics practices and lifelong learning skills in an introductory laboratory course
,” Am. J. Phys.
84
, 696
–703
(Sept
. 2016
).15.
E. G.
Cohen
and R. A.
Lotan
, eds., Working for Equity in Heterogeneous Classrooms: Sociological Theory in Practice
(Teachers College Press
, 1997
).16.
17.
D. M.
Desbien
, “Modeling Discourse Management Compared to Other Classroom Management Styles in University Physics
,” PhD thesis, Arizona State University
(2002
).18.
E.
Brewe
, “Modeling theory applied: Modeling Instruction in introductory physics
,” Am. J. Phys.
76
, 1155
–1160
(Dec
. 2008
).19.
One group of students explored the connection of this experiment to the concept of the center of mass as a “balance point” for their final project. https://www.youtube.com/watch?v=5I2NCp4MDXU.
20.
Berkeley Compass Project
, “Compass YouTube channel
,” https://www.youtube.com/user/berkeleycompass/videos (2012
).21.
One can even define a “slinkiness” parameter based on how much an object stretches under its own weight when suspended vertically.
22.
Arieh
Iserles
, A First Course in the Numerical Analysis of Differential Equations
(Cambridge University Press
, 2009
).23.
Exploring different choices in the implementation of the numerical simulation was the subject of one of the final projects. https://www.youtube.com/watch?v=OWy3lzXDcmY.
24.
This comparison was done qualitatively during instruction, but a quantitative comparison was the subject of a final project. https://www.youtube.com/watch?v=s0eIhpMeKZU.
25.
© 2018 American Association of Physics Teachers.
2018
American Association of Physics Teachers
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.