The equations of motion are
The normal mode frequencies are found by setting which gives which can be written in matrix form There is a non-trivial solution for , , and if and only if the matrix has zero determinant. Upon setting the determinant equal to and solving the resulting equation for , one will presumably find that is a solution. Plug into equation (16) and solve for , , and . This leads to which means that the motion corresponding to this normal mode is given by The statement that describes this motion is . Therefore, answer (B) is correct. |

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