Calculating Initial Velocity for a Projectile Across a Ravine

[nata620]

I can't figure this one out! Please help!

You are standing on the edge of a ravine that is 15 m wide. You notice a cave on the opposite wall whose ceiling is 7.9 m below your feet. The cave is 5.8 m deep and has a vertical back wall. You decide to kick a rock across the ravine into the cave. Acceleration is 9.8 m/s^2. 1)What initial horizontal velocity must you give the rock so that the rock barely misses the overhang?
2) How far down the back wall of the cave will the projectile hit?

Please help! THANKS!

 

[hage567]

You must show some effort in solving the problem before we will help you. What have you tried so far? What equations might you use? Show us your work.

 

[nata620]

well this is what i am thinking so far..because it is looking for initial velocity, i started off with the equation: x=vox *t and you are looking for vox=x/t. time is square root of 2y/g. and to plug in the the time into the vox equation given above. i am not sure if this is even remotely correct..

 

[hage567]

Sounds OK. So what did you get for an answer?