Relation between velocity and force

  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?
     
  2. jcsd
  3. Hootenanny

    Hootenanny 9,678
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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. ok, and whats the formula to find the force used in the increase of velocity? thanks by the answer gived by the way.
     
  5. ZapperZ

    ZapperZ 30,150
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    Er... F=ma!

    Zz.
     
  6. but thats when a = v^2/r in a circular movement. and on a rectilineous movement?
     
  7. Hootenanny

    Hootenanny 9,678
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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. ZapperZ

    ZapperZ 30,150
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    What?

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

    Zz.
     
  9. russ_watters

    Staff: Mentor

    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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