(20 14? Stroboscopic photography is a common experimental method to study the motion of objects. The camera is exposed at regular intervals.

(1) It takes 0.02s×3=0.06s for the ball to fall vertically from position A to position B, so the average speed of ball B is V = ST = 0.3m0.06s = 5m/s;

(2) The ball B moves in a straight line at a uniform speed, and the vertical upward resistance and vertical downward gravity of the ball B are a pair of equal balance forces, so the resistance of the ball B is equal to that of the ball B;

(3) The maximum speed reached by the first ball when falling at a uniform speed,

∴G=f，

∫f = KV2，

∴G=KV2=mg，

∴ Falling speed of the ball: v = mgk.

So the answer is: (1) 5; (2) equal to; (3)v=mgk。