1-5 Speed of a sinusoidal traveling wave

A wave traveling on a string is described by the equation


where y and x are expressed in meters and t is in seconds. Find
  1. the speed of the wave,

  2. the displacement of a particle on the string located at x = 0.50 m and at t = 2.0 s, and

  3. the acceleration of a particle on the string located at x = 0.20 m and at t = 3.5 s.

Example 4