$$m\mathop x\limits^{ \bullet \bullet } + c\mathop x\limits^{ \bullet \bullet } + k\left( {x - y} \right) = 0$$

$$m\left( {\mathop x\limits^{ \bullet \bullet } - \mathop y\limits^{ \bullet \bullet } } \right) + c\left( {\mathop x\limits^ \bullet - \mathop y\limits^ \bullet } \right) + kx = 0$$

$$m\mathop x\limits^{ \bullet \bullet } + c\left( {\mathop x\limits^ \bullet - \mathop y\limits^ \bullet } \right) + kx = 0$$

$$m\left( {\mathop x\limits^{ \bullet \bullet } - \mathop y\limits^{ \bullet \bullet } } \right) + c\left( {\mathop x\limits^ \bullet - \mathop y\limits^ \bullet } \right) + k\left( {x - y} \right) = 0$$

$$0.223$$ $$Ns/m$$

$$17.88$$ $$Ns/m$$

$$71.4$$ $$Ns/m$$

$$223.6$$ $$Ns/m$$

$$1.35$$

$$0.42$$

$$0.68$$

$$0.66$$

$$203.60$$

$$200.53$$

$$196.38$$

$$188.45$$