"Acceleration" does NOT mean speeding up. It also doesn't mean slowing down. Acceleration means ANY change in the speed OR DIRECTION of motion.
The only kind of motion that's NOT accelerated is motion at a steady speed AND in a straight line.
Even when your speed is steady, you're accelerating if your direction is changing.
A few examples: (no speeds are changing):
-- driving on a curved road, or turning a corner -- going around a curve on a skateboard, a bike, or a Segway -- running on a quarter-mile track -- an Indy car cruising a practice lap around the track -- water spinning, getting ready to go down the drain -- any point on the blade of a fan -- the little ball going around the inside of a Roulette wheel -- the Moon in its orbit around the Earth -- the Earth in its orbit around the sun
The reason the answer is 20m/second is because to find the speed of the ball in this question you have to divide the distance over the time giving you the result of 20m/second
