Hello student,
A sine wave has a maxima and a minima. The speed at the maximum and the minimum points are the same though the direction of motions are different. The difference between the positions of maxima and minima is equal to half of wavelength These positions are the antinodes.
Similarly the speed is equal to a maximum when the particle is at the nodes.
Thanks & Regards
Sumit Majumdar,
askIITians Faculty
Ph.D, IIT Delhi