Help With *Simple* Projectile Motion Problems

[shoez]

1. You accidentally throw your car keys horizontally at 5.0 m/s from a cliff 78 m high. How far from the base of the cliff should you look for the keys?




2. Maxiumu Horizontal Distance
Range = [Vi^2]/2 x (2sinTcosT)(G)

I know that it's a very simple problem, but I need help getting the steps down. I believe that the above formula is correct, but I could be wrong. If the above formula is correct, then how would I find the measurment of angle "T"?

-shoez

 

[aimslin22]

I think you are making it too complicated.

Write out your variables:

initial velocity:
final velocity:
distance:
time:
acceleration:

based on the variables you have, you should be able to use a distance formula.
I am unsure which variable you are using right now...

Hope this helps.

 

[shoez]

I think you are making it too complicated.

Write out your variables:

initial velocity:
final velocity:
distance:
time:
acceleration:

based on the variables you have, you should be able to use a distance formula.
I am unsure which variable you are using right now...

Hope this helps.

Well, it's a bit too late, I just submitted my final (and incorrect) answer to WebAssign. But here's what I know so far:

initial velocity: 5.0m/s
final velocity: (I believe it is irrelevant to the problem at hand.)
distance: (X)
time: (?) Unsure how to solve for time in this case.
acceleration: 9.8m/s (Gravity)

My teacher is a great guy, but he recently emigrated from Pakistan and has a very thick accent, which makes it difficult to understand him. I'm sure he instructed us to do solve the problems correctly, but I didn't come away with much on this subject.