Projectile Motion: Solve Time & Speed of Rock Leaving Bill's Foot

[huz521]

Projectile HELP!

Homework Statement

NOTE: IN THIS QUESTION, BILL KICKS
THE ROCKS HORIZONTALLY.
Bill kicks a rock off the top of his apartment
building. It strikes a window across the street
14 m away.
The acceleration of gravity is 9.8 m/s
2
.
If the window is 16 m below the position
where Bill contacted the rock, how long was
it in the air?
Answer in units of s.
How fast was it moving when it left Bill’s
foot?
Answer in units of m/s.

Homework Equations

The Attempt at a Solution

 

[iRaid]

(delta)y = v0t - 1/2gt^2just plug in the numbers

 

[fizzynoob]

>>just plug in the numbers

but that's not how you understand the physics of the problem.

Think about the question at hand and try to figure what is actually going on.

[PLAIN]http://img237.imageshack.us/img237/641/blockfc.png

V initial has only a horizontal component which equals its total magnitude.

Your knowns:

1) The final height
2) The total distance traveled
3) And Gravity

Know you must solve for time, which equation let's you solve for t by only knowing position and acceleration?

Know you must solve for V initial, what equation do you think you should use for this? (The derivative of position is velocity)