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The invention of a Newton, how was it measured back then?

  1. May 29, 2015 #1
    Hi, so I learned the definition of a newton which is

    Definition of newton
    - 1 Newton is the force needed to accelerate 1 kilogram of mass at the rate of 1 metre per second squared.
    - 1N = kg*(m/s^2)

    But I'm very curious about one thing
    What tools did he use, and how could newton actually measure the mass multiplied by the acceleration of an object precisely?
  2. jcsd
  3. May 29, 2015 #2

    Vanadium 50

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    Newton did not define the unit named after him. It wasn't named until over 200 years after his death.
  4. May 29, 2015 #3


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    Newton was not involved in the definition. The definition was needed in order to separate mass (which is independent of location) and weight (which is dependent on location).
  5. May 29, 2015 #4
    Thank you very much - both of you. A questions comes to mind as you mention this

    is it correctly understood that the weight of an object on earth is the force that the gravitational field exerts on that mass? So if the mass is 10kg then it's weight is 10kg*9,8N = 98Newton? (do you say the gravitational field exerts 9,8N force on a mass, or that the gravitational field makes the mass exert a force of 98Newton?)
  6. May 29, 2015 #5
    Both the statements are true - the mass exerts a 98N force on Earth, and the Earth exerts a 98N force on the mass (Newton's 3rd law). It's just that Earth has so much mass that we don't see it move much at all (Newton's second law).
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