It comes the time when you have the leisure time to spend for traveling. You have an idea to visit your relatives on the other town by using the train. Yet, sometimes we feel so bored and distressed finding out that our travel is still far to go. So, what can we do to overcome such kind of boring experience...

How does sound travel in solid materials? The transmission of sound can be illustrated by using a toy model consisting of an array of balls interconnected by springs. For real material the balls represent molecules and the springs represent the bonds between them. Sound passes through the model by...