Kinematics problem two stones falling one with velocity one at rest

1. Nov 16, 2005

bark00

hi please can sum one help me,

a stone is dropped from he top of a cliiff at rest another stone it thrown downwards from the same point at 11ms-1. The two stones land at the same time, what is the height of the cliff,

how do u work this out i have no idea,

thankyou in advance

bark00

2. Nov 16, 2005

Päällikkö

Which equations do you think you're supposed to use?

3. Nov 16, 2005

bark00

thankyou for helping me,

im not sure,
ive tried using combinations of v=u+at and s=1/2 (u+v)t but i dont know where to begin.

4. Nov 16, 2005

marlon

This is a gravity problem...Can you set up the equations for both velocity and position in the horizontal (x) and vertical (y) direction ?

ok, before actually giving specific information, i suggst you read this tutorial

The second formula you gave is not known to me. Are you sure of it ?

5. Nov 16, 2005

Galileo

Are you sure this is the question?
So you release one stone from rest and you throw the other one vertically down at 11 m/s from the same cliff and they land omn the ground at the same time? How's that possible?

Either I misunderstood the question, you copied it wrong or the height is zero and there would be no cliff.

6. Nov 16, 2005

bark00

hi thankyou all for the help i think i go it now i got the awnser as 128.6 metres approx

7. Nov 16, 2005

bark00

sorry missed out second one was trown a second later.

8. Nov 17, 2005

dx

The second formula is equivalent to $$s = V_{avg}t$$ for constant acceleration.

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