Glass prism Intermediate 01/21/2014 Light Deflection in Prism Glass Intermediate 01/21/2014 Prism with spectrum ray trace Intermediate 01/21/2014 Prism with tribeam Intermediate 01/21/2014 Crane pulley Intermediate 01/21/2014 A gun tackle pulley diagram Intermediate 01/21/2014 A gun tackle pulley Intermediate 01/21/2014 A double tackle pulley diagram Intermediate 01/21/2014 A double tackle pulley Intermediate 01/21/2014 Stone Arch Bridge Intermediate 01/17/2014