# Homework Help: An 80kg diver falls from a board into water 44m below the water.

1. Oct 26, 2009

### qomoco

1. The problem statement, all variables and given/known data
An 80kg diver falls from a board into water 44m below the water.

A)I found the potential energy of the diver on the board is 34496
B)kinetic energy as he stirkes the water=34496
C)I can figure out "how long does it take the diver to strike the water"

2. Relevant equations

3. The attempt at a solution
A)I found the potential energy of the diver on the board is 34496
B)kinetic energy as he stirkes the water=34496

2. Oct 26, 2009

### Delphi51

Welcome to PF, qomoco.
I think (a) and (b) are correct.
For (c), use one of your accelerated motion formulas. You know the acceleration, right?

3. Oct 26, 2009

### qomoco

the acceleration should be gravity? so 9.8m/s^2 but I dont know what's the accelerated motion formula.

umm. I took square root of (9.8x44x2) and got 29.36s but that's not right, the answer my teacher gave was 2.98s... can't figure out what I did wrong.

4. Oct 26, 2009

### Delphi51

The basic accelerated motion formulas are
a = Δv/Δt, Vf = Vi + at, d = Vi*t + ½*a*t²
You just have to pick out the one that makes use of your knowns and gives you the quantity you're looking for.

5. Oct 26, 2009

### Senjai

dont forget $${V_f}^2 = {V_o}^2 + 2ad$$ :)

6. Oct 26, 2009

### DaveC426913

It makes no sense that this guy is a diver. There are only two possibilities that make sense...
1] This is a two-part question. The second part deals with what happens after he hits the water.
2] You have misunderstood the question and/or mistranscribed it. Perhaps the ...

[ EDIT ] Oh. A swimmer diver.

I was picturing a guy in full scuba gear falling into the water from 120ft. It would kill him. Shows you where my head is at...

7. Oct 26, 2009

### Delphi51

Oh - 44 m is a pretty high diving board!
I guess the physics department computer needed a lot of random questions so it ran the range up a bit!

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