Units of force and acceleration in the context of gravity

Discussion in 'Physics & Math' started by black mask, Jul 23, 2016.

  1. Tiassa Let us not launch the boat ... Staff Member

    Yes, it does.

    Or, rather, it doesn't.

    Depends on one's context.

    Mine is clear.

    Look, it is possible to have a discussion in which you insistently spell out pages and pages of equations describing the physics of light itself, optics, thermodynamics, as well as diverse aspects of physical and electrical engineering requiring all the more math, and at no point in that particular discussion would it be untrue that you are describing the projection of a movie onto the screen.

    How is this difficult? Are you describing the physics of daisy farts?

    Okay, you know that trope about scientists being elitist and uncommunicative?

    And you're aware, I presume, that mythopoeic elements generally orbit some assertion of perceived truth?

    Yeah, this is an example of how that trope happens.

    Is it really so hard to acknowledge what that math describes?
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  3. DaveC426913 Valued Senior Member

    Perhaps we could split this into two threads:
    one about gravity and units
    and the other about the expectation of Russ and Rpenner living up to some higher standard than the rest of SciFo.
    Then all of us could open whichever thread contains things we expect it to contain.

    Or, failing that, we could just drop the meta-argument and stay on-topic.
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  5. arfa brane call me arf Valued Senior Member

    What math describes in physics, is real stuff that you can measure certain properties: mass, charge, momentum . . . of.

    Units in Newtonian Mechanics are the kilogram, meter (meter), and second. Forces, and other abstractions are compositions of the basic units.
    When you add Coulombs, units of charge, the convention is to carry over Newtonian forces, units kilogram-metre/second-squared, and Joules or units kilogram-metre-squared/second-squared. No Coulombs, but it's ok because Newtons and Joules don't get measured, space and time do.

    It's impossible as far as I know to do any Newtonian experiment without assuming mass exists.
    Something with weight, has that property because it has an "inertness" in a gravitational field.
    That's a bit like assuming numbers exist so you can do--math, or at least arithmetic.
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  7. James R Just this guy, you know? Staff Member

    Why don't you start with, say, the wikipedia article on gravity?

    Go off and do a bare minimum of reading for yourself, then come back here with some better questions.
  8. Confused2 Registered Senior Member

    Personally I would assume the term 'gravity' refers to 'gravitational field' unless otherwise specified.
    From memory the gravitational field is (by definition) the force on unit mass. By convention mass is measured in kilograms and force in Newtons so the gravitational field is (numerically) the force in Newtons per kilogram.

    Confused2 say the units of 'gravity' (gravitational field) are Newtons per kilogram.
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  9. The God Valued Senior Member

    What is worrisome is Tiassa's outburst over such a simple issue. This is second time in short period, once with wellwisher's ok looking harmless post and now here.
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  10. James R Just this guy, you know? Staff Member

    "Newtons per kilogram" is the same as "metres per second squared", which are the units of acceleration.
  11. Confused2 Registered Senior Member

    My emphasis was intended to be on 'gravity' as a field. Newtons per kilogram for a gravitational field, Newtons per Coulomb for an electrostatic field. In my post 'field' is repeated four times - possibly excessive (or wasted) emphasis.
    black mask likes this.
  12. James R Just this guy, you know? Staff Member

    Fair enough.

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