6 Specifics of Impact
Consider now the breaking process from the perspective of the target. When the
force of the strike is applied to the board or cinderblock, it accelerates in response to
that force. The key is that it does not accelerate uniformly—those areas where the
force is applied (the center of the target, if the strike is properly aimed) accelerate
much more than the outer regions of the target which are held in place by large
cinderblocks. This localized strain, the response to influence of stress imposed by the
strike, initiates the rupture. Strain is functionally the loss of height of the target that
occurs when the top surface is compressed and the bottom surface stretched. Because
of their molecular compositions, materials such as wood and cinderblocks withstand
compression better than stretching.