Transverse speed of string point when displacement is 12.0 cm

[zjm7290]

Homework Statement

The function y(x, t) = (15.0 cm) cos($$\pi$$x - 12$$\pi$$t), with x in meters and t in seconds, describes a wave on a taut string. What is the transverse speed for a point on the string at an instant when that point has the displacement y = 12.0 cm?

Homework Equations

I know that the equation of the wave is given above and the max transverse velocity is w*A and the max transverse acceleration is w^2*A and I know how to get the velocity of the wave in the x direction (propagation)

The Attempt at a Solution

I'm not sure where to even start, I think I need to find where 12.0cm is in reference to either distance or time, then I could just plug it into the wave equation, I'm just not sure how to get there. Any help would be greatly appreciated!

 

[zjm7290]

please guys! i have a final on this friday! anyone?