Finding original speed / acceleration

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Homework Help Overview

The discussion revolves around a kinematics problem involving a truck that covers a distance while decelerating. The participants are tasked with finding the truck's original speed and acceleration based on given parameters: distance, time, and final speed.

Discussion Character

  • Exploratory, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss using kinematic equations to solve for initial speed and acceleration, expressing confusion over variable identification and equation application.

Discussion Status

The conversation includes various attempts to clarify the relationships between the variables involved. Some participants suggest specific equations, while others express uncertainty about how to manipulate the equations effectively. There is no clear consensus on the correct approach yet.

Contextual Notes

Participants are navigating through the constraints of the problem, including the need to identify which values correspond to acceleration and initial velocity. There is also mention of confusion regarding the use of kinematic equations and the implications of the variables involved.

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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