The "Diaoyu Islands Incident" has always affected the patriotism of the military and civilians. In order to defend the territorial integrity, a certain unit of the Chinese Air Force held an unpreceden

The "Diaoyu Islands Incident" has always affected the patriotism of the military and civilians. In order to defend the territorial integrity, a certain unit of the Chinese Air Force held an unprecedented parachuting drill to protect the island. like

A. The slope of the graph line is decreasing within 0 to 10 seconds, indicating that athletes perform acceleration movements with gradually decreasing acceleration, and athletes perform deceleration movements with decreasing acceleration within 10 to 15 seconds. Therefore A is wrong.

B. At the end of 0 to 10 seconds, the athlete's speed begins to decrease and it is impossible to perform free fall motion. At the end of 15 seconds, the athlete begins to perform uniform linear motion. Therefore B is wrong.

C. Since the slope of the image is decreasing, the athlete opens the parachute at the end of 10s and then performs decelerating motion until the end of 15s. Therefore C is wrong.

D. From the end of 10s to the end of 15s, the speed is downward and decelerating in a linear motion, the acceleration direction is vertically upward, and the magnitude of the acceleration is gradually decreasing. Therefore D is correct.

So choose D