The differential equation governing the vibrating system is:
1
\(m\ddot x + c\dot x + k\left( {x - y} \right) = 0\)
2
\(m\left( {\ddot x - \ddot y} \right) + c\left( {\dot x - \dot y} \right) + kx = 0\)
3
\(m\ddot x + c\left( {\dot x - \dot y} \right) + kx = 0\)
4
\(m\left( {\ddot x - \ddot y} \right) + c\left( {\dot x - \dot y} \right) + k\left( {x - y} \right) = 0\)