Final answer:
Dean's acceleration as he slows down from 5.5 m/s to 1.0 m/s over 3 seconds is -1.5 m/s². The negative sign indicates deceleration.
Step-by-step explanation:
The subject of this question involves acceleration, which is a concept in physics describing the rate of change of velocity. To calculate the acceleration, we can use the formula a = Δv / Δt, where Δv is the change in velocity, and Δt is the change in time. Dean starts at a speed of 5.5 m/s and slows down to 1.0 m/s over 3 seconds. A stationary particle has a world line that is a vertical line parallel to the time axis, while the world line for a particle with constant velocity is a straight line inclined to the time axis. When considering a velocity vs. time graph, a horizontal line represents a constant velocity. The area under such a graph can be used to calculate the displacement of the particle over a given period. The change in velocity (5.5 m/s - 1.0 m/s) is -4.5 m/s, and the time interval is 3 seconds.
Using the formula, Dean's acceleration is calculated as:
a = Δv / Δt = (-4.5 m/s) / (3 s) = -1.5 m/s²
The negative sign indicates that Dean is slowing down, which is also called deceleration.