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curator:Tim Erickson
Hooke's Slinky

How well do slinkies obey Hooke's Law? Here are data taken with a Vernier force probe and a slinky stretched to various lengths—using different numbers of coils—on a smooth wooden floor.

You should find that each "sub-slinky" obeys the law pretty well. But what is the relationship between the spring constant you get and the number of coils we used?

What should happen? Given the same distance and a different number of coils, will you feel more force with more coils, or less force, or the same? And what does that have to do with the spring constant? See if you can explain the relationship you get physically.

coils is the number of coils.
dist_ft is the length of the stretched slinky in feet.
force_N is the force in Newtons, the pull on the force probe.

(data by Tim Erickson, Spring 2001)

coils
dist_ft
force_N
25
3
2.33
25
3.5
2.68
25
2.5
1.86
25
4
3.15
25
2
1.48
25
4.5
3.82
25
1.5
1.1
25
3
2.28
25
4
3.2
25
4.5
3.72
25
1
0.78
30
3
1.77
30
4
2.47
30
2
1.24
30
2.5
1.47
30
3.5
2.17
30
4.5
2.78
30
1.5
0.87
35
3
1.5
35
4
2.08
35
2.5
1.29
35
3.5
1.8
35
4.5
2.27
40
2
0.96
40
2.5
1.05
40
3
1.37
40
3.5
1.55
40
4
1.74
40
4.5
2.03
40
5
2.28
20
1.5
1.32
20
2
1.775
20
2.5
2.165
20
3
2.78
20
3.5
3.3
20
1
0.85

<text form of the data>

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Last updated 23 January 2003
supported by NSF award DMI-0216656