Relation between velocity and force

  1. Oct 26, 2008 #1
    Ok, so heres the question. To make a car move, we need a force, however, the velocity of the car is related to force? By example, we made a force to make the car start moving and the car started moving with a velocity of 10m/s. Then later the car has a velocity of 20m/s. So, the increase of the velocity is caused by a bigger force pushing the car? Cos, i do know that if the car is moving, then it has the tendence to keep moving with a constant velocity, it can only be stoped with a force in the opposite way to make it stop, so to make it go faster, then theres a force pushing it to go faster?
     
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  3. Oct 26, 2008 #2

    Hootenanny

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    Welcome to Physics Forums.

    I'm not sure that I entirely understand your question, but yes, to change an body's velocity there must be a net force acting on that body.
     
  4. Oct 26, 2008 #3
    ok, and whats the formula to find the force used in the increase of velocity? thanks by the answer gived by the way.
     
  5. Oct 26, 2008 #4

    ZapperZ

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    Er... F=ma!

    Zz.
     
  6. Oct 26, 2008 #5
    but thats when a = v^2/r in a circular movement. and on a rectilineous movement?
     
  7. Oct 26, 2008 #6

    Hootenanny

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    Newton's second law can be applied to any classical motion, when rectilinear or curvilinear.

    I just want to make sure that you know that the equation for acceleration that you quoted is only valid for circular motion.
     
  8. Oct 26, 2008 #7

    ZapperZ

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    What?

    Since when is F=ma only valid in circular motion?

    Zz.
     
  9. Oct 26, 2008 #8

    russ_watters

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    I also want to make sure you understand how Newton's first law applies to a car: the car decelerates when you take your foot off the gas pedal because there are forces acting to decelerate it. And when you add more gas, the car accelerates to a new equilbrium with its opposing forces. Force has no direct relationship with velocity, only acceleration.
     
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