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Help understanding Acceleration

  1. Jun 24, 2014 #1
    Hi,
    I just want to make sure I understand acceleration

    α = Δv / Δt
    α = vf - vi / tf - ti
    α = 8m - 0m / 4s - 0s
    α = 8m / 4s
    α = 2 m/s2



    So I know it has a constant acceleration of 2 m/s2
    what I want to know does this mean that the object will increase in acceleration for example
    I have two diagrams I created, now when the car accelerates does this mean at 1 second it is 2m/s2 and at 2 seconds it is increase by 4 m/s2 and at 3 seconds it has increased to 6 m/s2 and at 4 seconds it has increase to 8 m/s2

    Am I understanding this correctly help would be appreciated
     

    Attached Files:

  2. jcsd
  3. Jun 24, 2014 #2

    A.T.

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    Science Advisor
    Gold Member

    Unit of v is m/s not m.

    No, you don't know that. You computed the average acceleration based on initial and final velocity. You know nothing about how it changes in between.

    If the acceleration increases then it is not constant, as you claimed above.
     
  4. Jun 24, 2014 #3
    Acceleration ([itex]m/s/s[/itex] OR [itex]m/s^2[/itex]) describes changes in velocity [itex]m/s[/itex]. If acceleration is constant in this scenario then velocity will be CHANGING at a constant rate. So at 1 second the velocity will be [itex]2 m/s[/itex] NOT [itex]2 m/s^2[/itex] (this would be acceleration) and at 2 seconds the velocity will be [itex]4 m/s[/itex] NOT [itex]4 m/s^2[/itex]. Hope that helps
     
  5. Jun 24, 2014 #4
    It might help to think of 1 m/s^2 as "one meter per second per second", meaning that every second, the velocity changes by 1 m/s.
     
  6. Jun 24, 2014 #5
    Think of driving a car at a constant speed, say 40 miles/hour. or 40 k/hour. Then you press the gas pedal, going faster and faster and faster. You are now accelerating. You then press the gas pedal even more, your speed increase more, your acceleration increases.
    Usually in an actual problem in a text or homework you are given just one acceleration, you can assume its a constant, or average, acceleration. If you are given more than one acceleration value, you need the time that acceleration lasts to get a distance.
     
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