Question

A plane wave has a equation Y=25sin(120t-40x),Find the
a- wavelength,
b- wave velocity,
c -frequency of the wave,
d - period of the wave,
e -amplitude of the wave .
(where y and x are in meters,t is in seconds )

Answer 1

$\xi=A\sin(\omega t-kx+\phi_0)$

$y=25\sin(120 t-40x)$

We have

a) $k=2\pi/\lambda\to \lambda=2\pi/k=2\cdot3.14/40=0.157(m)$

b) $k=\omega/v\to v=\omega/k=120/40=3(m/s)$ (phase velocity)

c) $\omega=2\pi\nu\to\nu=\omega/(2\pi)=120/(2\cdot3.14)=19.1(Hz)$

d) $T=1/\nu=1/19.1=0.052(s)$

e) $A=25(m)$