# Spring Question parallel vs series?

1. Nov 16, 2007

### pauloemsu

1.When you pull with a constant force (F) what happens to delta x if the single spring is replaced with a) two identical springs in series? b) two identical springs in parallel? Assume all springs have the same spring constant and always compare to the single spring case?

2. The only equations i know of for this is hooke's law, but i'm not sure if that's relevant

3.I I would think that the springs in parallel would stretch less, but i don't know what they are asking in this question

2. Nov 16, 2007

### Bill Foster

You have to model multiple springs as a single spring, just like in a circuit problem with multiple resistors.

Two springs in series:

$$\frac{1}{k}=\frac{1}{k_1}+\frac{1}{k_2}$$

Two springs in parallel:

$$k=k_1+k_2$$

Check out http://en.wikipedia.org/wiki/Hooke's_law for more info.

3. Nov 17, 2007

### dynamicsolo

In the case of the parallel springs, both springs will stretch by the same amount because both are attached side by side to the mass. How much force will each spring have to provide to counterbalance the force F applied to the mass? How much will each spring stretch as a result?

In the case of the springs attached to each other "in series", when the force F is applied to the mass, how much will the "tension" be in the set of springs connected to the mass? How much will each spring stretch in response to that "tension"? What will be the total amount by which the set of springs stretches?

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