a ball rolls off the edge of a horizontal at 10m/s, what is the speed of the ball 2s later?

Answer 1

after 2 seconds, its downward speed is 10*2 = 20 m/s

So, you have a velocity with horizontal and vertical components of 10 and 20.

Now you can find the speed.

Answer 2

Or if your Physics teacher is picky vertical is 9.8 * 2 = 19.6