A stationary wave is represented by $\mathrm{y}=10 \sin \frac{\pi \mathrm{x}}{4} \cos 20 \pi \mathrm{t}$ where ' $\mathrm{x}$ ' and ' $\mathrm{y}$ ' are
expressed in $\mathrm{cm}$ and $^{\prime} t^{\prime}$ in second. Distance between two consecutive nodes is