1. **State the problem:** An airplane accelerates from rest to a lift-off velocity of 71 m/s in 26.1 seconds. We need to find the airplane's acceleration. 2. **Formula used:** Acceleration $a$ is defined as the change in velocity divided by the time taken: $$a = \frac{\Delta v}{\Delta t}$$ where $\Delta v$ is the change in velocity and $\Delta t$ is the time interval. 3. **Rearrangement:** The formula is already solved for acceleration, so no rearrangement is needed. 4. **Substitute the known values:** Initial velocity $v_0 = 0$ m/s (starting from rest), final velocity $v = 71$ m/s, and time $t = 26.1$ s. $$a = \frac{71 - 0}{26.1} = \frac{71}{26.1}$$ 5. **Calculate the acceleration:** $$a \approx 2.72 \text{ m/s}^2$$ 6. **Explanation:** Acceleration measures how quickly velocity changes over time. Since the plane starts from rest and reaches 71 m/s in 26.1 seconds, dividing the velocity change by the time gives the average acceleration. We keep three significant digits as given in the data. **Final answer:** The airplane's acceleration on the runway is approximately $2.72 \text{ m/s}^2$.