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

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1. Apr 12, 2016

### Zach_Sch

1. The problem statement, all variables and given/known data
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 .

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

3. 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 : )

2. Apr 12, 2016

### Staff: Mentor

Can you show your math at the end where you solve the two equations for m? That may help us spot any errors...

3. Apr 12, 2016

### Zach_Sch

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.