A wave disturbance in a medium is described by $y\left(x,t\right)=0.02\cos \left(50\pi t+\frac{\pi }{2}\right)$ $\cos \left(10\pi x\right),$ where x and y are in metre and t is in second

$A_R=2a\cos kx,$

$$\begin{gathered} \cos kx=1 for antinodes \\ kx=n\pi here k=10\pi \\ 10\pi x=n\pi \\ x=0.1m,0.2m.... \end{gathered}$$

for nodes

$$\begin{gathered} \cos kx=0 \\ kx=\left(2n+1\right)\frac{\pi }{2} \\ x=\frac{\left(2n+1\right)}{20}=0.05,0.15,... \end{gathered}$$

$V_w=\frac{cofft}{coffx}$