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Math help

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Enjoi.
Posts: 297 - Karma: 9
I've been trying to solve this for some time now and still cant get it.
Click for larger image

Hope you don't have too much trouble reading this :)
Dec 10 2009 9:55PM
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Enjoi.
Posts: 297 - Karma: 9
wth image didnt load...
Dec 10 2009 9:56PM
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Enjoi.
Posts: 297 - Karma: 9
nvm I was too impatient.
Dec 10 2009 9:56PM
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tommyp1ckles
Posts: 1337 - Karma: 55
its really hard to read...
Dec 10 2009 9:57PM
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thelittlebiggs
Posts: 173 - Karma: 10
Sorry can't really see it
Dec 10 2009 9:57PM
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Stuck.in.ohio
Posts: 331 - Karma: 36
divide by zero
Dec 10 2009 9:57PM
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ScuffDUFF
Posts: 2027 - Karma: 143
i cant even tell what kind of math that is by the picture.
Dec 10 2009 9:59PM
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Enjoi.
Posts: 297 - Karma: 9
Ok it says

While it was flying 5 m above a lake, a kingfisher spotted a fish and immediately swooped down. It entered the water 2 seconds later. It caught the fish and then came back up.
The kingfisher exited the water 2 seconds after entering it. It dropped the fish 1 second after coming out of the water.
In the following cartesian plane a portion of a parabola represents the height of the king fisher above the surface of the lake in relation to the time elapsed from the moment it spotted the fish.

At what height above the surface of the lake was the kingfisher flying when it dropped the fish?
Dec 10 2009 10:01PM
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tommyp1ckles
Posts: 1337 - Karma: 55
from what i can tell it looks like a quadratic problem; if he uploaded a good image itd prob be really easy to solve
Dec 10 2009 10:01PM
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Che~
Posts: 2108 - Karma: 296
im pretty sure its 2.5
Dec 10 2009 10:04PM
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EH_DUBS
Posts: 3080 - Karma: 969
i think so to.

if it takes 2 seconds to get to 5m and it dropped the fish after 1 second should be half way up?
Dec 10 2009 10:08PM
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NaturalRotater
Posts: 433 - Karma: 36
You sure this is math and not physics?
Dec 10 2009 10:14PM
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1337
Posts: 31054 - Karma: 29,248
thats what i was thinking
Dec 10 2009 10:16PM
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EH_DUBS
Posts: 3080 - Karma: 969
you probably have to make an equation for the parabola.

y=a(x-3)^2-h...

fuck i dont even remember how to do this shit haha. all i know know is fucking trig identities.

it dosent say how deep it went in the water hey? i dont know how to figure out where to start the parabola.
Dec 10 2009 10:20PM
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Enjoi.
Posts: 297 - Karma: 9
Nevermind I figured it out height is 1.875m
Dec 10 2009 11:36PM
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Slinger1x1
Posts: 8853 - Karma: 66
butttt
hes flying at a constant speed and so it takes 2.5m/s to get into the water. when he exits, he is flying at a lesser speed and most likely accelerating again (i didnt look the graph at all yet), so therefore the 2.5m/s probably doesnt apply after he comes out of the water.
Dec 10 2009 11:42PM
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Chickendodo
Posts: 1426 - Karma: 33
I think unless it's stated, the velocity would stay the same.  This is really more of a Physics problem than a math problem...
Dec 10 2009 11:44PM
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BackRoad
Posts: 299 - Karma: 46
physics is math
Dec 10 2009 11:46PM
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Slinger1x1
Posts: 8853 - Karma: 66
how could velocity stay the same? if you hit water at 5m/s, in the water there is friction and therefor your velocity would decrease, and when you leave the water, you cannot be going as fast as you were when you hit unless you accelerate up to that speed again

wait it an african kingfisher? or european? that could help...
Dec 10 2009 11:49PM
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no_steeze
Posts: 23992 - Karma: 4,273
plot the parabola on your calculator and trace until it his the x value of the bird's height and it'll tell you the y value, which is your height
Dec 10 2009 11:51PM
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Chickendodo
Posts: 1426 - Karma: 33
I lied (it's still a lot to do with physics, I swear). The answer is 1.875
You're given 3 points, (0,5), the initial point, (2,0), where the bird enters the water and (4,0), where the bird exits the water.

Then you do 3 equations of the form y = ax^2 + bx + c
first one comes out to c = 5

Then you just do simultaneous equations to find a and b
y = 4a + 2b + 5 (substitute 5 in for c)
y = 16a + 4b + 5

It figures out to a = 5/8 and b = -15/4

So the equation is then set to be y = (5/8)x^2 - (15/4)x + 5,
you plug in (5,?) and you get that the point where the bird drops the fish is (5, 15/8) or (5,1.875).

This was probably useless cause he already figured it out but oh well.
Dec 10 2009 11:56PM
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Chickendodo
Posts: 1426 - Karma: 33
In math they disregard these variables all the time haha, I would know, I'm a math major.  In lower level Physics they ignore them too, but once you start to do more advanced Physics they bring them into play.  It's more of a thought experiment, where it has constant velocity.

Listen. In order to maintain air-speed velocity, a swallow needs to beat its wings forty-three times every second, right?
Dec 10 2009 11:59PM
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no_steeze
Posts: 23992 - Karma: 4,273
yes, math always ignores resistance and velocity unless explicitly stated otherwise...just count on friction-free environments unless they say there's constant friction, resistance, or current
Dec 11 2009 12:03AM
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squibble
Posts: 4569 - Karma: 104
because math is stupid and it doesnt apply to life, it applies to other sciences
Dec 11 2009 12:08AM
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Clevinger
Posts: 394 - Karma: 8
Yeah fuck math, I just estimate my tax return.
Dec 11 2009 2:07AM
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