Two travelling waves of equal amplitudes and equal frequencies move in opposite directions along a string. They interfere to produce a stationary wave whose equation is given by $y=\left(10\cos \pi x\sin \frac{2\pi \mathrm{t}}{\mathrm{T}}\right)\mathrm{cm}$. The amplitude of the particle at $x=\frac{4}{3} \mathrm{cm}$ will be _____ $\mathrm{cm}.$