Spring Constant of Springs in Series and Parallel

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Spring Constant of Springs in Series and Parallel

Planning

The aim of this investigation is to examine the effect on the spring

constant placing 2 identical springs in parallel and series

combination has and how the resultant spring constants of the parallel

and series spring sets compare to that of a lone spring with identical

spring constant.

Hypothesis

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Hooke's Law states that "The magnitude of the spring constant (k) is

equal to the stretching force applied (F) divided by the resultant

extension (x)", it should be possible to determine a spring constant

for each spring set.

Due to existing knowledge of springs I propose that the series spring

set will have a lower spring constant (and hence due to Hooke's Law

display a greater extension) than the parallel spring set. Also, as

Hooke's Law is a linear function, the spring constant of the series

spring set should be exactly half that of a single spring, whereas the

spring constant of the parallel set should be exactly double that of

the single spring. This also means that if the resulting extension or

spring length of the spring sets are graphed along a y axis with the

increasing force mapped to the x axis (so that the results can be

displayed in a traditional scientific graph fashion), the gradient

will be the inverse of the spring constant.

This hypothesis is backed up by many sources, one such source is

"Physics" by Ken Dobson, David Grace and David Lovettwhich in the 2000

edition states on page 90 that the spring constant of 2 springs in

series is k = k/2 and for 2 springs in parallel k = 2k

This hypothesis will probably only hold true however while the spring

extends at a directly proportional rate to the increase in force on

the spring. This is because every material has an elastic limit which

is the percentage of extension a piece of material can be stretched to

and still return to its original form. As the magnitude of extension

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