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Acceleration and constant speed question

  1. Jan 30, 2005 #1
    Can someone tell me which of the these is true or false and possibly explain it to me?

    a)The acceleration of a car is zero when it is turning right at a constant speed
    b)The acceleration of a car is zero when it is driving up a long straight incline at constant speed
    c)The acceleration of a car is zero when it is topping the crest of a hill at constant speed
    d)The acceleration of a car is zero when it is bottoming out at the lowest point of a valley at constant speed
    e) The acceleration of a car is zero when it is speeding up as it descends a long straight decline.

    Any help would be great.

    thanks
     
  2. jcsd
  3. Jan 30, 2005 #2

    dextercioby

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    What are your answers/hunches and the reasoning behind them...??

    Daniel.

    P.S.Read the "sticky" at the top of the thread...
     
  4. Jan 30, 2005 #3

    DB

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    These are fairly easy questions if you just Think. Consider acceleration as the rate of change in speed, in your case ou can even think of it as a change in speed. Think of forces dependent on inclinations.
     
  5. Jan 30, 2005 #4
    Make sure you know exactly what acceleration is. In order for an object to accelerate, its velocity must be changing.
     
  6. Jan 30, 2005 #5

    dextercioby

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    THE VELOCITY VECTOR MUST BE CHANGING WITH TIME AS TO HAVE A NONZERO ACCELERATION VECTOR...

    Daniel.
     
  7. Jan 31, 2005 #6
    Is this correct?
    a) false because direction is changing
    b) true
    c) true
    d) true
    e) false because magnitude of the accerlation is changing
     
  8. Jan 31, 2005 #7

    dextercioby

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    The way i see it,only B is true...

    Daniel.
     
  9. Jan 31, 2005 #8
    why does your argment for a not apply to c and d?
     
  10. Jan 31, 2005 #9

    HallsofIvy

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    Unfortunately, thinking THAT way will lead you to the wrong answer to at least one of these. Think "velocity" not "speed"!
     
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