Simple Harmonic Motion on a moving platform

[chrisy2012]

I had my physics midterm today and I totally blanked out. I want to know how to solve it for next time.

So In the picture, there are two springs connected to the mass on a platform.
a) if the platform is at rest, find the angular frequency

the expression for angular frequency is :ω=√(k/m), so I just added the two k's and plugged it into k and got :ω=√((k1+k2)/m). Is this correct?

b)The platform then started to move in SHM with the equation d(t)=D*cos10∏t. We had to find the amplitude of mass M. This is where I tripped up and don't know how to solve it. Any ideas?

 

[tiny-tim]

hi chrisy2012!

the expression for angular frequency is :ω=√(k/m), so I just added the two k's and plugged it into k and got :ω=√((k1+k2)/m). Is this correct?

maybe!

how would you prove it? ​

b)The platform then started to move in SHM with the equation d(t)=D*cos10∏t.

find the positions of the two endpoints as functions of t, and that will help you find the distances to multiply by the spring constants