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Calling all math gurus

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Calling all math gurus

Old 08-13-06, 09:20 PM
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Calling all math gurus

Could someone please halp me out with this quadratic function?

s(t)=-16t^2 + 40t + 4
where s is the height in feet and t is the time in seconds. Find the time it takes the ball to return to the height of 4 feet when thrown from a platform.

Thank you in advance.
Old 08-13-06, 09:24 PM
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12.
Old 08-13-06, 09:36 PM
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You shouldn't wait until the last minute to start your homework.
Old 08-13-06, 10:09 PM
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Originally Posted by Bronkster
You shouldn't wait until the last minute to start your homework.
Damnit, took my answer!
Old 08-13-06, 10:16 PM
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Originally Posted by Bronkster
You shouldn't wait until the last minute to start your homework.
Why? We still give him the answer...
Old 08-13-06, 10:26 PM
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2.6. Just a guess.
Old 08-13-06, 10:28 PM
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The square root of pi times i. Now give me a hard one.
Old 08-13-06, 10:38 PM
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Is the person throwing/dropping the ball male or female?
Old 08-13-06, 10:43 PM
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too bad i threw away my math book after my refresher algebra course a few years back and don't feel like writing anything on paper

from what i remember of this stuff, it seems like an easy problem
Old 08-13-06, 10:50 PM
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11:50 Pm
Old 08-13-06, 10:53 PM
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Is it an African or European ball?
Old 08-14-06, 06:07 AM
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Q: How can you drop an egg 6 ft with out breaking it?

A: Drop it off an 8 ft ladder.
Old 08-14-06, 06:39 AM
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Originally Posted by cseaw
Could someone please halp me out with this quadratic function?

s(t)=-16t^2 + 40t + 4
where s is the height in feet and t is the time in seconds. Find the time it takes the ball to return to the height of 4 feet when thrown from a platform.

Thank you in advance.
I'm not doing your homework, but the answer is don't try to use the quadratic equation. Plug in 4 on the left side and simplify. When factoring the equation is trivial by inspection, the quadratic equation should be avoided. Save it for a rainy day when you really need it.
Old 08-14-06, 07:02 AM
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How high is the platform?
Is the ball thrown vertically or horizontally?
We know that the acceleration due to gravity is 32 ft/second.
Old 08-14-06, 07:53 AM
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ummm.. this isn't going to work. There's no minus sign in your equation. That ball is going higher and higher until it heads out of orbit!

C'mon people, isn't anybody paying attention????
Old 08-14-06, 07:53 AM
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Originally Posted by jon-w9
How high is the platform?
Is the ball thrown vertically or horizontally?
We know that the acceleration due to gravity is 32 ft/second.
Don't forget to apply the vector field for wind resistance.
Old 08-14-06, 08:21 AM
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what olddude said. this is pretty simple.
Old 08-14-06, 08:22 AM
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Assuming the ball is moving relative to the platform and the platform is moving away from you at the speed of light... never.
Old 08-14-06, 09:44 AM
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Originally Posted by drmoze
ummm.. this isn't going to work. There's no minus sign in your equation. That ball is going higher and higher until it heads out of orbit!

C'mon people, isn't anybody paying attention????
There is, I missed it at first as well.

The formula is:

s(t) = -16t^2 + 40t + 4

Just do what the OldDude said.
Old 08-14-06, 09:59 AM
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s(t) = -16t^2 + 40t + 4

Seriously you need this solved??? It's trivial, but if having someone else do your homework for you is going to give you good grades OK.

If we've a value for s of 4 we get:

4 = -16t^2 + 40t + 4

Therefore

-16t^2 + 40t = 0

Therefore

16t^2 = 40t

Dividing both sides by t we get

16t = 40

Therefore

t = 40/16 = 2.5
Old 08-14-06, 10:05 AM
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yeah let's give him the answer and when he has a test, he can post here and asks too
Old 08-14-06, 10:09 AM
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Originally Posted by cseaw
Could someone please halp me out with this quadratic function?

s(t)=-16t^2 + 40t + 4
where s is the height in feet and t is the time in seconds. Find the time it takes the ball to return to the height of 4 feet when thrown from a platform.

Thank you in advance.
4 = -16t + 40t + 4
0 = -16t + 40t

so t = 0
Old 08-14-06, 10:16 AM
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Originally Posted by nodoubt
yeah let's give him the answer and when he has a test, he can post here and asks too
Ahh, but you miss my point, my attempt here is not to give him the answer but to leave him failing his test.

Like you I recognised this as an attempt to get someone else to solve some homework for him. So I did it.

If he's this lazy he can use my answer, I'll even answer others for him if he wants. Because in the end his laziness costs him not me. Because he fails all his exams.

Even if he passed exams he'd fail in life. I'm not going to try to prevent that if he's this lazy I'm happy to see him fail and even help him on his way.
Old 08-14-06, 10:20 AM
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genius plan
Old 08-14-06, 12:11 PM
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Originally Posted by jon-w9
There is, I missed it at first as well.

The formula is:

s(t) = -16t^2 + 40t + 4

Just do what the OldDude said.
Yup. What he said. I missed it. Gotta learn not to post before morning coffee...

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