讲解当前题目---Here is the extracted content from the image:
**Question Stem:**
【例 2】 如图所示，一同学沿直线行走，现用频闪照相记录了他行走中的9个位置的图片，观察图片，能大致反映该同学运动的速度-时间图像的是
**Illustrative Image Description:**
* **Type:** A sequence of 9 identical stick figures representing a person at different positions, arranged horizontally.
* **Main Elements:** The figures are spaced along a horizontal line. Starting from the leftmost figure, the distance between successive figures increases progressively towards the right. This indicates that the person is moving from left to right and is speeding up (accelerating). The initial distance between the first few figures suggests an initial non-zero velocity.
**Options:**
Each option presents a velocity (v) versus time (t) graph. The horizontal axis represents time (t) and the vertical axis represents velocity (v). The origin (0) marks both zero velocity and zero time.
* **Option A:**
* **Type:** Line chart.
* **Description:** The graph is a straight line with a positive slope, passing through the origin. It starts from a negative velocity, linearly increases to zero velocity, and then continues to linearly increase into positive velocity. This represents constant acceleration where the object changes direction of motion.
* **Annotation:** Above this graph, there is an arrow depicting a path: moving to the right, then making a U-turn, and moving to the left. This arrow visually represents the change in direction from negative to positive velocity.
* **Option B:**
* **Type:** Line chart (piecewise linear).
* **Description:** The graph shows three distinct phases:
1. A horizontal line segment in the positive velocity region, indicating constant positive velocity.
2. A horizontal line segment at zero velocity, indicating the object is at rest.
3. A downward sloping line segment from zero velocity into the negative velocity region, indicating increasing speed in the negative direction (acceleration in the negative direction).
* **Option C:**
* **Type:** Line chart (piecewise).
* **Description:** The graph shows two main parts:
1. An upward sloping straight line segment in the positive velocity region, starting from a positive initial velocity and linearly increasing. This indicates constant positive acceleration.
2. A vertical dashed line followed by a horizontal dashed line in the negative velocity region. This suggests an instantaneous change from the final positive velocity to a constant negative velocity. The horizontal dashed line indicates constant negative velocity.
* **Option D:**
* **Type:** Line chart (piecewise linear).
* **Description:** The graph shows two distinct phases:
1. An upward sloping straight line segment starting from zero velocity, linearly increasing into positive velocity. This indicates constant positive acceleration from rest.
2. A horizontal line segment in the positive velocity region, indicating constant positive velocity.
**Answer:**
答案: C