Ball a is dropped from the top of a building and hits the ground in 10 seconds. another ball b is thrown straight down from the same building one second after dropping ball a. neglect air resistance and consider g - 9.8 m/s2 . what should be the initial velocity of ball b so that it hits the ground simultaneously with ball a: select one: o a. 9.8 m/s b. 20.6 m/s c. 4.3 m/s d. 10.3 m/s