# Two different springs in parallel

## Homework Statement

In a parallel spring system, the springs are positioned so that the 56N stretches each spring equally. The spring constant for the left-hand spring, kl, is 1.7Nm and the spring constant for the right-hand spring, kr, is 7.7Nm.[/B]

## Homework Equations

Momentum Principle
s=mg/2k
ks= mg/s
[/B]

## The Attempt at a Solution

I'm confused with how they'll stretch the same length.. need help

(1.7N/m)(56N)= 95.2m
(7.7N/m)(56N)= 431.2m[/B]

Last edited:

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Chestermiller
Mentor
Check the units on your two equations.

If each spring stretches x meters, what is the force for each of the springs (in terms of x)? If the sum of the two spring forces is 56 N, what is x equal to?

Chet

gneill
Mentor
Is that the entirety of the problem statement or was there a specific question associated with the description? Is there any other context we need to be aware of? A diagram perhaps?

Check the units on your two equations.

If each spring stretches x meters, what is the force for each of the springs (in terms of x)? If the sum of the two spring forces is 56 N, what is x equal to?

Chet
Is that the entirety of the problem statement or was there a specific question associated with the description? Is there any other context we need to be aware of? A diagram perhaps? gneill
Mentor
Ah. Much clearer! The two springs are constrained to stretch by the same amount, and both contribute to the total force that supports the weight. You have to figure out what amount of stretching will result in the desired total.

Ah. Much clearer! The two springs are constrained to stretch by the same amount, and both contribute to the total force that supports the weight. You have to figure out what amount of stretching will result in the desired total.
Would I use s = mk/2k ? I am confused on this question because I am not sure how to find an equal stretch with a constant force between the two springs.

Chestermiller
Mentor
Would I use s = mk/2k ? I am confused on this question because I am not sure how to find an equal stretch with a constant force between the two springs.
Why don't you try answering the questions I posed in post #4? These will lead you directly to the answer.

Chet