Aball is thrown straight up into the air, with an initial speed of 28.2 m/s. how fast is it moving after 1.00 s?

The acceleration of gravity is 9.8 m/s per second.  If gravity is
the only force acting on an object and the object is free to move,
then its downward speed grows by 9.8 m/s every second.  If it
happens to be moving up, then its upward speed shrinks by 9.8 m/s
every second, until it runs out of upward gas and starts falling.

If the upward speed of the ball is 28.2 m/s at some point in time, then
its upward speed is  (28.2 - 9.8) = 18.4 m/s one second later.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.