An earthquake hits Los Angeles! A wave ripples down the LA Freeway at a speed of 150 mph, with crests 60 m apart. Motorists caught by the quake are shaken up and down inside their cars violently. The road moves so quickly that, after pushing cars up to a peak height at a crest, the asphalt almost leaves the tires behind as they fall into a trough.

In other words, at its fastest, the asphalt of the road moves downward at the same rate that the cars and tires fall down into the troughs of the wave.

Write an equation for this wave of the form

       y(x, t)  =   A  *  sin ( k*x  -  ω*t )