posted by Becca (question two of four!) on .
A ball is thrown vertically upward with a speed of 25.0 m/s from a height of 2.0 m.
How high does the ball rise? How long does it take to reach its highest point? How long does the ball take to hit the ground after it reaches its highest point? What is the ball's velocity when it returns to the level from which it started?
I don't know how to set this up... the equations that I have use more than just initial velocity and acceleration... am I supposed to assume the final velocity or distance?
thanks for your time!!
For ball thrown upwards,
Y = 2 + 25 t - (g/2)t^2
The highest point is attaned when
V = 25 t - gt = 0
Solve for that time, and insert that t in the first equation to get the maximum height.
When the ball returns to the point where it was thrown, the speed will be the same as it started (because of conservation of energy!) but the direction will have changed.
v = 25t-(9.81)t = 0
I'm confused about that. how can 15.19t equal zero? Or am a going too far with that step?