What are the two distinct phases of the RPG-7 blast wave?

The two distinct phases of the RPG-7 blast wave are the positive and negative pressure phases. In the context of explosive or high-velocity projectile blasts, the blast wave generated consists of an initial high-pressure phase followed by a lower pressure phase.

The positive pressure phase occurs first, characterized by a rapid increase in pressure above atmospheric levels, which can cause significant damage upon impact with structures or personnel. This is followed by the negative pressure phase, where the pressure drops below ambient levels, resulting in a vacuum-like effect that can cause further structural damage due to the pulling forces created.

Understanding these phases is crucial for assessing the impact of an RPG-7 on its targets and for formulating appropriate tactical responses. The other options, such as expansion and contraction or shock and thermal phases, do not accurately define the specific phases associated with the blast wave of an RPG-7, leading to confusion in targeting and damage assessment. Initial and final phases provide no clear distinction relevant to the mechanics of blast waves.