Need help finding Kinematic formula for Initial V

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Krasz
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Homework Statement


A truck covers 60.0 m in 9.0s while smoothly slowing down to final speed 3.00 m/s.
Find the initial velocity.


Homework Equations


Vi +1/2at^2 has two unknowns
V= vo + at has two unknowns
x= v^2 - Vi^2/2a has two unknowns
v^2=vi^2 +2a(xf-xi) has two unknowns


The Attempt at a Solution


I have been scouring the internet looking for a formula that can solve for V initial excluding acceleration that can work! I can't seem to find any! How do I go about finding the initial velocity?
 

Discussion

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Variables you have: final velocity v, displacement s, and time t. Which one of the four classic kinematics equations excludes the acceleration a?
 
Fightfish said:
Variables you have: final velocity v, displacement s, and time t. Which one of the four classic kinematics equations excludes the acceleration a?

I can't believe I overlooked that! Thank you!
 
You have to use two equations
vf = vi - at...(1)
x = vi*t - 1/2*a*t^2 ...(2)
substitute the value of vi from the first equation in the second equation and solve for vi.