This diagram shows a pulse in a thin string proceeding at uniform speed of 4cms^-1 to the right with amplitude 1.5cm and wavelength 2cm. It is just about to meet with a thicker string in which its speed will be 2cms^-1. At this stage, the pulse will be partially reflected 180 degrees out of phase in the thin string with an amplitude of 0.5cm and partially transmitted in phase in the thick string with an amplitude of 1cm. Copy the diagram on graph paper and, underneath draw a diagram to show the situation 2s later.
http://imgur.com/CZMQK1O
http://imgur.com/CZMQK1O