# Finding mass of an object on a spring, given Frequency

## Homework Statement

A mass m at the end of a spring oscillates with a frequency of 0.84 Hz . When an additional 730 g mass is added to m, the frequency is 0.65 Hz .

## Homework Equations

f*2pi = w
w = (k/m)^1/2
f = (1/2pi)*(k/m)^1/2

## The Attempt at a Solution

I simply used the third equation twice, rearranging to the following:
m = k/(2pi*f)^2
using this equation two different times I ended up with:
m = k / (2pi*.84)^2
m + .73 = k / (2pi*.65)^2
I solved the above equations for m and came out with the wrong answer.

Any help is greatly appreciated! Thanks in advance : )

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berkeman
Mentor

## Homework Statement

A mass m at the end of a spring oscillates with a frequency of 0.84 Hz . When an additional 730 g mass is added to m, the frequency is 0.65 Hz .

## Homework Equations

f*2pi = w
w = (k/m)^1/2
f = (1/2pi)*(k/m)^1/2

## The Attempt at a Solution

I simply used the third equation twice, rearranging to the following:
m = k/(2pi*f)^2
using this equation two different times I ended up with:
m = k / (2pi*.84)^2
m + .73 = k / (2pi*.65)^2
I solved the above equations for m and came out with the wrong answer.

Any help is greatly appreciated! Thanks in advance : )
Can you show your math at the end where you solve the two equations for m? That may help us spot any errors... Can you show your math at the end where you solve the two equations for m? That may help us spot any errors... Haha, so I attempted to solve my systems of equations three different times and got a very large negative mass, I just attempted it again and got the correct answer.
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