Photographic experiment process

(1) Method 1: According to △ h = gt 2, g = △ h t 2 is obtained.

Method 2: calculate the instantaneous speed of a certain position (the average speed in a certain period is equal to the instantaneous speed in the middle); Then use v=gt to solve, g = v t.

(2) VB = XAC2T = (28.4-12.5) ×10-22× 0.04m/s =1.99m/s.

Therefore, the speed of the ball passing through point B is 1.99 m/s. 。