Question

A standing wave is represented by $Y=5cos(200t-0.05x)$ where Y and A are in metres, t is in seconds and x is in metre. Velocity of wave is

• A. $10$m/s
• B. $4\times {10}^3$ m/s
• C. $0.00025$ m/s
• D. $4000$m/s

Answer 1

Answer: (D)

$4000$m/s

Given that

$Y=5cos(200t-0.05x)$

we can write a= 5

$\omega =200$

$\frac{2\pi }{\lambda }=\frac{1}{20}$

$\lambda =40\pi$

$wavevelocity=V=\frac{\lambda }{T}$

$V=\frac{40\pi \times \omega }{2\pi }$

$V=\frac{8000}{2}$

$V=4000\frac{m}{s}$