Need help finding Kinematic formula for Initial V

AI Thread Summary
To find the initial velocity of a truck that covers 60.0 m in 9.0 seconds while slowing to a final speed of 3.00 m/s, two kinematic equations are needed. The equations vf = vi - at and x = vi*t - 1/2*a*t^2 can be used together. By substituting the expression for initial velocity from the first equation into the second, the initial velocity can be solved. The key is to recognize that acceleration is not directly needed in the final calculation. This method effectively utilizes the known variables of final velocity, displacement, and time.
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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?
 
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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.
 
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