Posted by ashley on Thursday, September 15, 2011 at 10:47pm.
A ball is thrown vertically upward with a speed of +13.0 m/s.
(a) How high does it rise? (b) How long does it take to reach its highest point? (c) How long does the ball take to hit the ground after it reaches its highest point?
(d) What is its velocity when it returns to the level from which it started?

physics  Henry, Saturday, September 17, 2011 at 7:32pm
a. h = (Vf^2  Vo^2) / 2g,
h = (0  (13)^2) / 19.6 = 8.62m.
b. t(up) = (Vf  Vo) / g,
t(up) = (0  13) / 9.8 = 1.33s.
c. d = Vo*t + 4.9t^2 = 8.62,
13t + 4.9t^2 = 8.62,
4.9t^2 + 13t  8.62 = 0Use Quadratic Formula to find t:
t = 0.55s.
d. Vf^2 = Vo^2 + 2gd,
Vf^2 = 0 + 2*9.8*8.62 = 168.952,
Vf = 13m/s. = Same as initial velocity
going up.