- #1

ksrivatsan

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Hi,

I'm just training for the 2013 F=ma exam, and I took some old exams. I tried to do the 2012 exam, and could not figure out problem 21. Can anyone help me, please?

A spring system is set up as follows: a platform with weight 10 N is on top of two springs, each with a spring constant of 75 N/m. On top of the platform is a third spring with spring constant 75N/m. If a ball with weight of 5.0 N is fastened to the top of the third spring and then slowly lowered, by how much does the height of the spring system change?

(A) 0.033 m

(B) 0.067 m

(C) 0.100 m (correct answer)

(D) 0.133 m

(E) 0.600 m

F=kx

The bottom springs act as one spring with K=150 N/m, thus will contract 0.033 m under the weight

The top spring will compress 0.067 m under the weight

so is it just addition...?

I'm just training for the 2013 F=ma exam, and I took some old exams. I tried to do the 2012 exam, and could not figure out problem 21. Can anyone help me, please?

## Homework Statement

A spring system is set up as follows: a platform with weight 10 N is on top of two springs, each with a spring constant of 75 N/m. On top of the platform is a third spring with spring constant 75N/m. If a ball with weight of 5.0 N is fastened to the top of the third spring and then slowly lowered, by how much does the height of the spring system change?

(A) 0.033 m

(B) 0.067 m

(C) 0.100 m (correct answer)

(D) 0.133 m

(E) 0.600 m

## Homework Equations

F=kx

## The Attempt at a Solution

The bottom springs act as one spring with K=150 N/m, thus will contract 0.033 m under the weight

The top spring will compress 0.067 m under the weight

so is it just addition...?

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