question: What term always refers to acceleration in the direction opposite to the direction of the velocity and always reduces speed, unlike negative acceleration?
distractor3: calibration
distractor1: progression
distractor2: extraction
correct_answer: deceleration
support: Misconception Alert: Deceleration vs. Negative Acceleration Deceleration always refers to acceleration in the direction opposite to the direction of the velocity. Deceleration always reduces speed. Negative acceleration, however, is acceleration in the negative direction in the chosen coordinate system. Negative acceleration may or may not be deceleration, and deceleration may or may not be considered negative acceleration. For example, consider Figure 2.14.