How can you find displacement given initial position, velocity, and time?

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To find displacement given initial position, velocity, and time, it's crucial to use the correct equations for motion. The equation x = xi + vt + 1/2at^2 applies only under constant acceleration, which is not the case here due to changing acceleration. The user initially calculated displacement incorrectly by using an inappropriate initial velocity. After some discussion, they realized the mistake and corrected their approach. This highlights the importance of using the right initial conditions and equations for varying acceleration scenarios.
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Homework Statement


physicscut.jpg

xi=2.0
ti=0

i know the acceleration is -2.0 @ t=3 using the change v/ change t (rise over run)
the vx@ t=3 is two
and t=3
so i need to find the position of x
so i pluged in the formula x= xi+vt+1/2vt2 and I get 11..but I'm way off

Homework Equations



see above

The Attempt at a Solution



tried a few times working from going from the initial x all the way and I get 11 again.

Am I not entering in the sig figs right or am i way off?

I just found this forum and love it!
 
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That equation is for constant acceleration only.
The acceleration changes in this problem, so that equation will not work.

How do you get displacement from velocity in general?
 
Redbelly98 said:
That equation is for constant acceleration only.
The acceleration changes in this problem, so that equation will not work.

How do you get displacement from velocity in general?


i figured it out
I wasn't using the right vi

got me on the right path thanks!
 
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