The Vertical Displacement Y(x, T) of a Horizontal $y ( x , t ) = ( 6.00 \mathrm {~mm} ) \cos \left[ \left( 3.25 \mathrm {~m} ^ { - 1 } \right) x - \left( 7.22 \mathrm {~s} ^ { - 1 } \right) t \right]$

Essay

The vertical displacement y(x, t) of a horizontal string aligned along the x -axis is given by the equation $y ( x , t ) = ( 6.00 \mathrm {~mm} ) \cos \left[ \left( 3.25 \mathrm {~m} ^ { - 1 } \right) x - \left( 7.22 \mathrm {~s} ^ { - 1 } \right) t \right]$
What are the (a) speed and (b) amplitude of this wave?