This applet will help you to visualize rotating a function around the axis. You can input a function in the textbox in the upper left hand corner, and then set the domain in the adjacent textboxes (note that the domain is limited to a maximum of -10 < x < 10). Once you have inputted the information, clicking the "New" button will create the function. To rotate the function around the x axis click the "+" and "-" buttons to increase and decrease the rotation respectively. You can move the camera by clicking and dragging on the applet at any time.