Answer :

average speed is defined as distance traveled divided by time duration to cover the distance.

So  average Speed =  100 cm / 2 seconds  = 50  cm / second

Answer: 50 centimeters per second.

Explanation: The ball travels a distance of 100cm in a span of 2 seconds, then, the speed of the ball can be calculated as:

S = (distance moved)/(total time) = 100cm/2s = 50cm/s

So the average speed of the ball is 50 centimeters per second.