The transverse displacement of a string fixed at both ends is given by $-y,x$  are in meter $y=0.06\sin \left(\frac{2\pi x}{3}\right)\cos \left(120\pi t\right)$  and $t$  in sec the length of string is 1.5 m and its mass is $3\times {10}^{-3}kg$ . Find amplitude at point $x=0.5m$.