Finding original speed / acceleration

AI Thread Summary
To find the truck's original speed and acceleration, two key kinematic equations are used: x = v0*t + 1/2 * a*t² and v² = v0² + 2*a*x. Given that the truck covers 40.0 m in 8.50 s and ends with a speed of 2.80 m/s, the initial speed (v0) and acceleration (a) need to be calculated. The confusion arises in identifying which values correspond to acceleration and velocity, as well as how to manipulate the equations to isolate the variables. Ultimately, the calculations should lead to determining the original speed and acceleration without assuming v0 is zero.
mrserv0n
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Im new to this stuff so bear with me. I am really only looking for help as to what equation I use to find these answers.

A truck covers 40.0m in 8.50s while smoothly slowing down to a final speed of 2.80 m/s.

A. Find the trucks original speed.

B. Find the its acceleration.
 
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try using solving for 2 variables, initial speed and acceleration, in 2 equations:
x = v0*t + 1/2 *a*t2
and
v2 = v02 + 2*a*x
 
Im confused as to which is number is my accelartion and which is my velocity
 
you know 3 variables, x = 40.0m, t = 8.50s, and v = 2.80m/s
you need to find v0, the initial speed, and a, the acceleration

use your knowledge of algebra to find these 2 variables in 2 equations
 
Sorry to bring this post back from the dead -- but I'm doing this problem right now, and is V0 supposed to be 0? If I use formula VFinal: 2.80 m/s = V0 + AT (A being unknown at this point) and T being 8.5 seconds...

I'm left with a mad scramble of algebra where V0 = .33m-A

I'm constantly getting confused as to what to use when in these kinematics equations.

a(acceleration) = Vf-V0/T

a= 2.8m/s - V0 / 8.5 s

How would I go about plugging that in...that would still leave me with two variables none of which I seem to be able to solve for.
 
Is Vo supposed to be 40 m/ 8.5 s to get 4.71 m/s initial velocity?
 
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