Check my work

So, simply put, here's what I've done so far and just need someone to glance over it and check for the most glaring (I already know I messed some things up) mistakes:
http://img388.imageshack.us/img388/3677/egrproblem5dq.jpg [Broken]

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Chi Meson
Homework Helper
Why are you using 1 s for time?

Chi Meson said:
Why are you using 1 s for time?
Just as a stopgap kind of, until I get the recording of what the actual times were. It's only temp, I just wanted to try and get the calcs right and in order, then fix the # inputs later.

So, how's it look?

Anyone?

Bump

Please, will someone just look over what I did and comment?

lightgrav
Homework Helper
Well, there's no diagram, so I can't really tell,
but I expect that the stretch of the spring was NOT in the x-direction only,
and that the y-component of velocity was a direct result of the spring's PE.
[ie, 1/2 k s^2 = 1/2 m v^2 , not just (v_x)^2].

you could solve horizontal eq'n for landing time t
as a function of variable v_0 and measured x_f
then insert in vertical equation, so you solve directly for (v_0)^2

lightgrav said:
Well, there's no diagram, so I can't really tell,
but I expect that the stretch of the spring was NOT in the x-direction only,
and that the y-component of velocity was a direct result of the spring's PE.
[ie, 1/2 k s^2 = 1/2 m v^2 , not just (v_x)^2].

you could solve horizontal eq'n for landing time t
as a function of variable v_0 and measured x_f
then insert in vertical equation, so you solve directly for (v_0)^2
Okay, here's a quick diagram:
http://img267.imageshack.us/img267/3533/diagram6gl.jpg [Broken]

How could I solve for time using v0 if I don't have v0? I used the xf=x0 + v0x*cos(theta)*t +(1/2)*a*t^2 to find the v0x, and the same deal for v0y. But was that right or not? I still have not gotten the correct times, but is there any way to figure them out with what I have?

All I need in the end is the spring constant for the system and to show equations describing it's motion/flight (like how far it would go with the particular v0 it shot with). But I keep confusing myself on what it is I'm actually calculating...

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Wow, the more I go over this problem, the more confused I get....especially since I don't have v0 to begin with, which is just throwing me off.

Could someone just help me with a little more in-depth layout of the steps? I've done several projectile problems before, but I always seem to mess up one or two steps and throw the whole thing off...

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Bump...just need someone to help with an outline of the steps/equations I should have to get what I need

This is an AWESOME resource....well, as long as someone pays attention to your question....

Anyone? Just take a look over my work and help me straighten out the steps to get what I need

Chi Meson
Homework Helper
Hey. If it took 2.5 seconds to travel 6.2 m horizontally, why are you using 1 s in your calculations? Your formulas look correct, now find (initial speed) (cos 30)= (horizontal distance)(2.5 s).

So I'm finding initial speed again using:
v0*(cos 30)=dist*(2.5s) ?

Is that all?

What about the spring constant, k, at the end? What velocity figure do I use? Since I have like 10 of them, that was confusing me, as to which one I actually plug in down there...

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??????????

Yet again....

Chi Meson