(20 13? Stroboscopic photography is a commonly used experimental method to study the motion of objects. Photography was taken in a dark room, and the shutter was always open, but

(1) A ball moves the same distance at the same time, and A moves in a straight line, so A moves in a straight line at a constant speed.

B moves different distances in the same time, and B moves in a straight line, so B moves in a variable speed straight line.

(2) The ball A moves in a straight line at a uniform speed, and the vertical upward resistance of the ball A and the vertical downward gravity are a pair of equal balance forces.

When B moves in an accelerated straight line, its gravity is greater than its resistance.

A and B have the same gravity, so the resistance of A is greater than that of B. 。

(3) It takes 0.02s×5=0. 1s to vertically fall from position A to position B, and 0.02s×3=0.06s for ball B, so it takes longer for ball A than for ball B. 。

So the answer is: (1) unification; Variable speed; (2) A; Greater than; (3)0. 1; be more/bigger than