The displacement of a stretched string is given by

PHYSICS · Single correct · A Level · Physics · Waves · Waves

Problem

y=0.05\cos(4x+120t)

, with

x

and

y

in metres and

t

in seconds. Which of the following correctly specifies the wave’s speed and the direction in which it travels? (a)

30\,\text{m\,s}^{-1}

toward

+x

(b)

30\,\text{m\,s}^{-1}

toward

-x

(c)

4.8\,\text{m\,s}^{-1}

toward

-x

(d)

480\,\text{m\,s}^{-1}

toward

-x