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April 19, 2014

April 19, 2014

Posted by **Bob** on Sunday, October 3, 2010 at 3:57pm.

(a) What is your reaction time?

(b) What is the magnitude of the deceleration?

I tried eliminating the values in order to find accel and time, but the values canceled out and when I tried separating them, I got the answer wrong. What am I doing wrong?

- Physics -
**bobpursley**, Sunday, October 3, 2010 at 4:07pmI dont see how it is solvable, unless you assume the acceleration is different on each, or the time during deacceleartion is the same.

You have as variables: a, time to slow, tr.

- Physics -
**Bob**, Sunday, October 3, 2010 at 4:22pmLet me try to clarify

v1=22.222 m/s

v2=13.278 m/s

x=vi(t)+1/2a(t^2)

56.7=22.222t+1/2a(t^2)

24.4=13.278t+1/2a(t^2).

Through elimination

32.3=8.94t

t=3.611s

From there I separated to -vi=at as vf is 0

-22.222=a(3.611)

-13.278=a(3.611)

-35.5=7.222a

a=-4.92 m/s^2

- Physics -
**Bob**, Sunday, October 3, 2010 at 4:30pmForgot to put my question at the end of it XD

This is from me trying to interpret what you've done in the previous times this question has been asked, but obviously, I'm wrong somewhere. At what point in the work am I messing up?

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