Question

Two students are on a balcony a distance h above the street. One student throws a ball vertically downward at a speed vi; at the same time, the other student throws a ball vertically upward at the same speed. Answer the following symbolically in terms of vi, g, h, and t. (Take upward to be the positive direction.)

Find the velocity of each ball as it strikes the ground.
For the ball thrown upward vf =
For the ball thrown downward vf =

Please help, this is my last problem I need help with.

Answer 1

For the ball thrown upward:
\[vf=vi-g*t\]
for the ball thrown downward:
\[vf=vi+g*t\]
When ball goes up "g" is opposing to movement then "g" is negative.
When ball goes down "g" is positive because it increases velocity.

Answer 2

answer of both part remains same and it is vi+g*t.