Special Relativity using diagrams

Abstract

We present some diagrams which can be useful to help the teacher when it is necessary to explain some of the most important aspects of Special Relativity for High School students, or first year undergraduate students. These diagrams can be used to construct some simple instruments to demonstrate effects like time dilation and size contraction. We propose also a construction, with an equivalent pendulum in order to demonstrate the difference in time advance between two reference systems: the first in rest relatively to the observer and the second in movement relatively to the same observer.