Solution

ID: past-exam-of-the-mathematical-methods-ii-course-of-the-university-of-oxford/2017/9/c/solution

The squared-frequency matrix is
The dimensionless spring matrix has an orthonormal eigenbasis
with eigenvalues . Adding the gravitational term therefore gives
The uniform mode leaves both springs unstretched. The other two modes deform the springs and so have higher frequencies.

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