Stroboscopic photography is a common experimental method to study the motion of objects. As shown in figure ABCD, the ball shot by the camera (every 0. 1) is different.

Test analysis: stroboscopic photography is a method to study the movement of objects, which can record the trajectory and speed change of the movement of objects. When a moving object is subjected to a balancing force, it maintains a state of uniform linear motion. Uniform linear motion means that the route it passes is straight and the speed is constant.

A, the trajectory is a curve, and the speed gradually increases; B, the trajectory is straight, and the speed increases gradually; C, the trajectory is straight, and the speed gradually decreases; D, the trajectory is straight, and the speed is constant.

So choose D.

Comments: Correctly reading the physical information reflected by stroboscopic photos is the key to solving the problem. The bigger the difference between two points in the photo, the faster the speed, the smaller the difference and the slower the speed.