Traditional Culture Encyclopedia - Photography major - As shown in the picture, photographers

As shown in the picture, photographers

C

Test analysis: the length of AB is l = 0.02m, and the time for pebbles to go from A to B is 0.001s. According to the uniform linear motion, the instantaneous speed at the middle moment is equal to the average speed of this period, that is, the instantaneous speed at the middle moment of AB is v = 20 m/s, and the height of pebbles falling from the static state is h, so V2 = 2gh, and h = 20m is solved.