Traditional Culture Encyclopedia - Photography major - Usually "stroboscopic photography" is used to study the motion of objects. Photography is done in a dark room, the camera is fixed, the shutter is always open, and it is done with a flash.

Usually "stroboscopic photography" is used to study the motion of objects. Photography is done in a dark room, the camera is fixed, the shutter is always open, and it is done with a flash.

The distance between two photos measured with a scale is about: 2.40 cm = 0.024 m.

The moving speed of the object: v = ST = 0.024m0.02s =1.2m/s. 。

So choose B.