19. A student on a bicycle decided to determine his acceleration when coasting down a steep hill.The student started from a full stop and reached a velocity of 8.75m/s in 3.8 s. What was his average acceleration?Assume that downhill is the positive direction. 20. A car enters a highway travelling 14m/s[N] . After 5.5 s. the car reaches a velocity of 28m/s[N] . What was the car's average acceleration?

**19. Calculating average acceleration of the bicyclist:**<br /><br />* **Given:**<br /> * Initial velocity (vᵢ) = 0 m/s (started from rest)<br /> * Final velocity (vₙ) = 8.75 m/s<br /> * Time (t) = 3.8 s<br /><br />* **Formula:** Average acceleration (a) = (vₙ - vᵢ) / t<br /><br />* **Solution:**<br /> a = (8.75 m/s - 0 m/s) / 3.8 s<br /> a = 8.75 m/s / 3.8 s<br /> a ≈ 2.30 m/s²<br /><br />* **Answer:** The student's average acceleration was approximately 2.30 m/s² down the hill.<br /><br /><br />**20. Calculating average acceleration of the car:**<br /><br />* **Given:**<br /> * Initial velocity (vᵢ) = 14 m/s [N]<br /> * Final velocity (vₙ) = 28 m/s [N]<br /> * Time (t) = 5.5 s<br /><br />* **Formula:** Average acceleration (a) = (vₙ - vᵢ) / t<br /><br />* **Solution:**<br /> a = (28 m/s [N] - 14 m/s [N]) / 5.5 s<br /> a = 14 m/s [N] / 5.5 s<br /> a ≈ 2.55 m/s² [N]<br /><br />* **Answer:** The car's average acceleration was approximately 2.55 m/s² [N].<br />