Error cs0117: 'UnityEngine.Component' does not contain a definition for 'velocity'

I am currently studying a tutorial ( link :http://unity3d.com/learn/tutorials/modules/beginner/2d/2d-controllers ), and after I copied the script he wrote (time :44:88) i transferred the script to my Sprite and received this error: Error cs0117: ‘UnityEngine.Component’ does not contain a definition for ‘velocity’
Please help. Thank you.

hey, I just solved this problem myself, you now have to use GetComponent(). instead of rigidbody2D/Rigidbody2D