• May 1st 2010, 08:48 PM
mode
I think this is the right section to post this but im not 100%

Find the time required for a train to reach 100m if Vo=20m/s (not sure how to do subext) and acceleration is $.5m/s^2$
$
s=20t+(1/2).5t^2
$

As far as i know, this is solved using the quadratic formula. How would i go about putting this equation into quadratic form so i can use the quadratic formula?
• May 1st 2010, 08:51 PM
pickslides
Quote:

Originally Posted by mode
$
s=20t+(1/2).5t^2
$

As far as i know, this is solved using the quadratic formula. How would i go about putting this equation into quadratic form so i can use the quadratic formula?

make $a = \frac{1}{2}\times 0.5 = 0.25$ , $b= 20$and $c= 0$
• May 1st 2010, 08:54 PM
mode
would the 2nd number always be a? and would the first nuumber always be b?
• May 1st 2010, 09:02 PM
pickslides
Quote:

Originally Posted by mode
would the 2nd number always be a? and would the first nuumber always be b?

No, for $at^2+bt+c = 0 , t= \frac{-b\pm\sqrt{b^2-4ac}}{2a}$

Do you follow?
• May 1st 2010, 09:15 PM
mode
yea i do know i was just confused as to where the numbers would go in the quadratic form. But a little thinking has pulled me through but thanks for your help:)