Difference between revisions of "Talk:135: Substitute"

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(fixed date)
(Answered Question 1.)
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:Yes, I've fixed the date on the page. [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 15:30, 14 September 2012 (UTC)
 
:Yes, I've fixed the date on the page. [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 15:30, 14 September 2012 (UTC)
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1. It takes the raptor 25m/s / 4m/s^2 = 6.25s to reach it's top speed, during which I can run 6.25s * 6m/s = 37.5m.  Add on my 40m head start, and I can reach a spot 77.5m away from the raptor before he gets me.  In the same time, the raptor can run 4m/s^2 * (6.25s)^2 / 2 = 78.125m.  I'm eaten before he's fully up to speed. 
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Therefore, I have to solve for when the raptors location, r(t) = 4m/s^2 * t^2 /2 - 40, and my location, m(t) =  6m/s*t, are equal.  Dropping units, we get 2t^2 -40 = 6t, or 2t^2 - 6t - 40 = 0.  Dividing by 2 I get t^2 - 3t - 20=0.  Using the quadratic equation, I get (3 +/- sqrt(89))/2, roughly equal to 6.217s and -3.217s.  Plugging that back into m(t), I get 37.302m for my terminal run. [[User:Blaisepascal|Blaisepascal]] ([[User talk:Blaisepascal|talk]]) 22:18, 14 September 2012 (UTC)

Revision as of 22:18, 14 September 2012

Rikthoff (talk) The issue date is off, as i can't find a create date for the image. Can anyone fix?

Yes, I've fixed the date on the page. lcarsos (talk) 15:30, 14 September 2012 (UTC)

1. It takes the raptor 25m/s / 4m/s^2 = 6.25s to reach it's top speed, during which I can run 6.25s * 6m/s = 37.5m. Add on my 40m head start, and I can reach a spot 77.5m away from the raptor before he gets me. In the same time, the raptor can run 4m/s^2 * (6.25s)^2 / 2 = 78.125m. I'm eaten before he's fully up to speed. Therefore, I have to solve for when the raptors location, r(t) = 4m/s^2 * t^2 /2 - 40, and my location, m(t) = 6m/s*t, are equal. Dropping units, we get 2t^2 -40 = 6t, or 2t^2 - 6t - 40 = 0. Dividing by 2 I get t^2 - 3t - 20=0. Using the quadratic equation, I get (3 +/- sqrt(89))/2, roughly equal to 6.217s and -3.217s. Plugging that back into m(t), I get 37.302m for my terminal run. Blaisepascal (talk) 22:18, 14 September 2012 (UTC)