1. **Problem:** Describe the shape of the distance-time graph and explain what it tells us about the car's speed. The graph starts at the origin and rises steeply, then levels off forming a concave curve. **Explanation:** - The steep rise at the beginning means the car is covering a lot of distance in a short time, so the speed is high. - As the graph levels off, the distance increases more slowly over time, indicating the car is slowing down. - The concave shape shows the speed is decreasing over time. 2. **Problem:** How to find the car's average speed between two points A and B on the graph? **Formula:** $$\text{Average speed} = \frac{\text{Change in distance}}{\text{Change in time}} = \frac{d_B - d_A}{t_B - t_A}$$ **Explanation:** - Points A and B represent positions on the graph with coordinates $(t_A, d_A)$ and $(t_B, d_B)$. - The average speed is the slope of the straight line connecting A and B. - This slope tells us how fast the car traveled on average between those two times. This method gives a single speed value representing the overall motion between A and B, regardless of any speed changes in between.