8 25.3 consequences of Einstein's postulates Conclusion: lengths measured perpendicular to the direction of motion are unaffected by the motion length oriented along the direction of motion asure Measure by by us in lab Fairy godmother 0I y=l=0=b0V1-(v2/c2) T ro I o is the proper length 8 25.3 consequences of Einsteins postulates Conclusion: The length l is shorter than lo when measured in a frames in which it is moving The proper length is longest in all measurement. ength contraction only occurs for those lengths(or components of lengths )oriented along the direction of motion. 1818 Conclusion: lengths measured perpendicular to the direction of motion are unaffected by the motion. 2length oriented along the direction of motion x y x′ y′ O O′ Measured by us in lab Measure by Fairy godmother 0l τ l 0 τ 0 0 0 τ γτ l l v = = 0 τ l v = 1 ( ) 2 2 0 0 l v c l l = = − γ §25.3 consequences of Einstein’s postulates l0 is the proper length. Length contraction only occurs for those lengths (or components of lengths ) oriented along the direction of motion. Conclusion: The length l is shorter than l0when measured in a frames in which it is moving. §25.3 consequences of Einstein’s postulates The proper length is longest in all measurement