A transversal wave travels on a medium with linear density m1=1 and finds a medium with m2.
while the elastic constants are the same.
As a result, part of the wave bounces (it is reflected).
Notice the different polarities in the reflected wave depending on whether m2 is larger or smaller than m1.
Observe the dependence of wave velocity and pulse width.
Also, notice the difference in the two ends: The end on the left is fixed, the one on the right is free.