The two distinct phases of the blast pressure effect are...

The two distinct phases of the blast pressure effect are...

• A. Positive Phase
• B. Positive Phase and Negative Phase
• C. Initial Phase and Final Phase
• D. Early Phase and Late Phase

Answer: (B)

The blast pressure effect has two phases: a positive phase, where the front of the wave creates an overpressure above ambient, and a negative phase, where the pressure drops below ambient as the wave passes and rarefaction follows. The positive phase delivers the immediate peak pressure that drives the initial impulse and potential damage; the negative phase follows with suction-like forces from the underpressure, which can cause additional injuries or effects as pressures rebound. This pairing—positive phase and negative phase—is why that option is the best answer, because it accurately describes the two distinct pressure states the blast wave produces. Terms like initial/final or early/late don’t reflect the sign change in pressure and the sequence the wave undergoes.

The blast pressure effect has two phases: a positive phase, where the front of the wave creates an overpressure above ambient, and a negative phase, where the pressure drops below ambient as the wave passes and rarefaction follows. The positive phase delivers the immediate peak pressure that drives the initial impulse and potential damage; the negative phase follows with suction-like forces from the underpressure, which can cause additional injuries or effects as pressures rebound. This pairing—positive phase and negative phase—is why that option is the best answer, because it accurately describes the two distinct pressure states the blast wave produces. Terms like initial/final or early/late don’t reflect the sign change in pressure and the sequence the wave undergoes.