Posted by Patrick on .
a ball is thrown vertically upward from the ground with the velocity of 30m/s. a) how long will it take to rise to its highest poitn? b) how high does the ball rise? c) how long after projection will the ball have a velocity of 10m/s? d) what is the total time of flight?

Physics 
tchrwill,
a ball is thrown vertically upward from the ground with the velocity of 30m/s. a) how long will it take to rise to its highest poitn? b) how high does the ball rise? c) how long after projection will the ball have a velocity of 10m/s? d) what is the total time of flight?
From Vf = Vo  gt, 0 = 30  9.8t yielding t = 3.06 sec.
From h = Vo(t)  g(t^2)/2, h = 30(3.06)  4.9(3.06)^2 yielding h = 45.88m.
From Vn = Vo  gt, 20  9.8t yielding t = 2.04 sec.
Since the fall time equals the rise time, the total flight time is 2(3.06) = 6.12 sec. 
Physics 
bfreeman,
How do we handle something without a symetrical rise/fall time. An object thrown vertically from a window is the basis of this question