Frequency of mass oscillating between two springs in series

[patrick4]

Homework Statement

I've had some problems trying to work through this problem:

Two springs of stiffness k1 and k2 are attached in succession to a mass m. What is the frequency of vibrations in terms of the spring stiffness k1 and k2 and the mass m?

Homework Equations

f=(1/2pi)sqrt(k/m)

I think that is the only relevant equation, but I am not entirely sure.

The Attempt at a Solution

I am confused at weather or not I need to multiply or add the two spring constants. Or, if I need to make two separate equations with the frequencies being constant in both equations.

I tried to relate it to the energy of a spring, but I didn't have a displacement so that equation would not work.

Any help would be greatly appreciated, Thanks!

 

[lanedance]

try 2 dispalcement variables
the end of the first spring
the end of the 2nd spring

write down the force vs distance equation of each spring & so find the expression for the 2 combined by equating the force