Resistors/Spring Constant

1. Mar 16, 2007

||spoon||

Hey, i am about to undertake an EPI at school in which i will be testing the spring constants of singular springs, and then of a few springs, both in parrallel and in series.

Before i start the prac i noticed that the equations for the overall spring constant of springs in series/parrallel are opposite to the equations for resistors in series/parrallel... i.e the equation for spring constant in series is the same as that for the resistors in parrallel.

What significance does this hold, if any?

Thanks for any input

-Spoon

2. Mar 16, 2007

lpfr

The formulas are similar because the mathematical behavior is the same. There are no physical similarities.

For two springs in parallel, the total force is the sum of each two forces. For resistors, the total current is the sum of the two currents. Formulas are similar, but you cannot assimilate forces to currents.

3. Mar 16, 2007

||spoon||

sorry im not sure that i understand your explaination... if the sum of the forces in parrallel for a spring is just sprinbg one plus spring 2 etc... if the resistor equation works of the same principal would the equation for resistors in parrallel also be the resistance 1 plus resistance 2...it isnt however.. 1/R total = 1/R1 + 1/R2

Could you please try and explain again im sorry i think i have just mis understood

Thanks

Spoon

4. Mar 16, 2007

lpfr

In the case of two springs in parallel, when you stretch the two springs of the same amount (L) the total force will be:
Ft=F1+F2= Lk1+Lk2=Lkt
Then:
kt=k1+k2
For resistors, if a current I traverse the two resistors in series the voltage at the ends of two resistors will be:
Vt=V1+V2=IR1+IR2=IRt
Then:
Rt=R1+R2
You can do the same derivation imposing a force to two springs in series and imposing a voltage to two resistors in parallel.

The formulas are similar for (springs in parallel and resistors in series) and for (springs in series and resistors in parallel)

Same mathematical behavior does not mean physical similitude.

Last edited: Mar 16, 2007
5. Mar 16, 2007

Mentz114

It works for capacitors too, if you reverse 'series' and 'parallel'.