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Is Is acceleration due to gravity and gravity same thing?

  1. May 3, 2009 #1
    Is Is "acceleration due to gravity" and "gravity" same thing?

    Is "acceleration due to gravity" and "gravity" same thing? If not what are they measured in (units)?

    cheers,
    Alip.
     
    Last edited by a moderator: May 12, 2009
  2. jcsd
  3. May 3, 2009 #2

    Doc Al

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    Staff: Mentor

    Re: gravity?

    The acceleration due to gravity is (obviously) an acceleration, and thus has units of m/s^2. The term "gravity" labels a kind of interaction, so it's not clear what specific aspect you are referring to. What do you mean by it? The force of gravity, perhaps? (Give an example.)
     
  4. May 3, 2009 #3
    Re: gravity?

    In my engineering class, we were asked to tell the unit of the Gravity by our teacher. I said "Newton" but my teacher wrote metre per second squared. who's correct? I knew that was the unit for "acceleration due to gravity" but I din't say anything because some people use "gravity" term for "acceleration due to gravity".

    cheers,
    Alip.
     
  5. May 3, 2009 #4
    Re: gravity?

    here, by "gravity" i mean the interaction between two masses but I don't know what "gravity" my teacher was refering to.
     
  6. May 3, 2009 #5
    Re: gravity?

    I will second what the knowledgeable Doc Al has said. Asking what the units of 'gravity' are is a poor question, and doesn't make sense. As a loose example of what Doc Al is saying, imagine asking what the units of 'electromagnetism' are, for instance.

    Gravitational force, i.e.:

    [tex]
    F=\frac{G m_1 m_2}{r^2}
    [\tex]

    is a force - the force of attraction due to gravity between two bodies of masses m1 and m2, and is measured in Newtons.

    Acceleration due to gravity (something I imagine you will be more familiar with) is oft given as 'little g':

    [tex]
    g=\frac{Gm}{r^2}
    [\tex]

    - and as you have correctly stated, this has units of acceleration. It's worth thinking that gravity itself isn't a measureable quantity as such, it's the effects of gravity that we quantify.
     
  7. May 3, 2009 #6
    Re: gravity?

    oh ok, I am sort of clear now. my teacher shouldn't have asked the unit of "Gravity", that's so stupid and made me confused; rather he should have asked the unit of "Force of Gravitation". I did Force of Gravitation in Standard 10 and it was really interesting.

    cheers,
    Alip.
     
  8. May 3, 2009 #7

    A.T.

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    Science Advisor
    Gold Member

    Re: gravity?

    Newtonian gravity is modeled as a field with a field strength measured in units of acceleration. Newtons are a unit of the "force due to gravity" exerted on a certain mass, which is equal to the field strength times the mass.
    No, he should have asked you for the unit of the gravitational field strength, to get the answer he wanted.
     
    Last edited: May 3, 2009
  9. May 4, 2009 #8
    Re: gravity?


    thanks for all the answers.
     
  10. May 8, 2009 #9
    Re: gravity?

    the term force represents the resistive action which may decrease your velocity or increase. the change of velocity which is uniform is called acceleration.here acceleration due to gravity value is 9.8 m/s^2 and we feel the earth is making to change our change in velocity by 9.8 m/s per second.this change is observed or assumed to be force .so for unit body(1kg) is 9.8N or simply 9.8 m/s^2. and for whole body is its x times the 9.8 N or 9.8m?s^2
    so for very unit level the force of gravitation and acceleration of gravity is same . They give the same physical meaning .But for whole mass its multiple of X.So this gives the quantum nature of gravity.
     
  11. May 8, 2009 #10
    Re: gravity?

    thanks.
     
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