Final answer:
The average acceleration of the body during the 3rd second is -4 m/s², because the acceleration is constant at this value throughout the body's motion.
Step-by-step explanation:
Average Acceleration Calculation
To find the average acceleration of a body moving along the x-axis with a position function displacement(t) = 4t - 2t2, we must examine the body's velocity function and how it changes over time. The velocity function is the first derivative of the position function with respect to time, which yields v(t) = 4 - 4t. Acceleration is the derivative of the velocity function with respect to time, which gives a(t) = -4 m/s2. This indicates that the acceleration is constant.
To find the average acceleration during a specific interval, say between times t1 and t2, you would typically calculate the change in velocity over the change in time. However, because the acceleration is constant in this case, the average acceleration over any interval is the same as the instantaneous acceleration at any point in time. Therefore, the average acceleration during the 3rd second (from t=2s to t=3s) is simply the constant acceleration of -4 m/s2.