A few butterflies and many moth species spin a silk case or cocoon prior to pupating, while others do not, instead going underground. A butterfly pupa, called a chrysalis, has a hard skin, usually with no cocoon.
4. tension - (physics) a stress that produces an elongation of an elastic physical body; the direction of maximum tension moves asymptotically toward the direction of the shear. natural philosophy, physics-the science of matter and energy and their interactions; his favorite subject was physics.
Before we can get to how to create and release visual tension we need to understand what it is. Consider the following definitions of tension. tension (n). 1  physical or mental strain or stress. 2  a force created through stretching or pulling.3  the interplay of conflicting elements.hat is Visual Tension. Before we can get to how to create and release visual tension we need to understand what it is. Consider the following definitions of tension. tension (n). 1  physical or mental strain or stress. 2  a force created through stretching or pulling. 3  the interplay of conflicting elements.