How do the processes of foliation and bedding act as destructive forces of rock layers?

In a voltaic cell, electrons flow from the (positive/negative) to the (positive/negative) terminal.

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

Why does lightning travel from clouds to the ground?