The displacement of particles in a string stretched in the x-direction is represented by y.among the following expressions for y, those describing wave motion are

Options

A. `cos k x sin omegat `
B. `k^(2) omega^(2) - omega^(2) t^(2)`
C. `cos^(2) (k x + omega t)`
D. `cos (k^(2) k^(2) - omega^(2) t^(2))`

Answer

A, C

Explanation

(a) and (c ) represent a wave motion as they satisfy the condition
`f (x, t) = f (x, t, + T) and f (x, t) = f (x + lambda, t)`