posted by stan .
A ball is thrown vertically upward with a
speed of 23.7 m/s from a height of 2.0 m.
How long does it take to reach its high-
est point? The acceleration of gravity is
2) How long does the ball take to hit the ground after it reaches its highest point?
(1) The ball reaches its highest point when g*t = 23.7 m/s, because that is where the vertical velocity component becomes zero.
t = 23.7/g = 23.7/9.8 = 2.4 seconds. It matters not what height the ball is thrown from, for this part.
(2) The highest point will be at a distance
Vo*t - (g/2)t^2 = 28.7 m above where it was thrown from. That will be 30.7 m above the ground.
Now all you have to do is compute the new time required to fall that distance. Call it t'
Use 30.7 m = (g/2)*t'^2 and solve for t'.