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anonymous

  • 4 years ago

what is the work done BY A PERSON in carrying an object against gravity a. positive b. negative

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  1. JamesJ
    • 4 years ago
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    Positive, as it adds energy to the object. By working against gravity, the person is taking the object higher from the surface of the earth. Hence the change of the gravitational Potential Energy of the object is positive, and therefore the work done on the object by the person must also be positive.

  2. anonymous
    • 4 years ago
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    that's exactly what i thought but my physics teacher said that W=energy gained=mgh and since g is negative therefore work done is negative what do u say 'bout this.

  3. JamesJ
    • 4 years ago
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    If at the surface of the earth, I lift a 1 kg mass up 1 meter, then it has higher gravitational PE to the tune of \[ PE = mgh = g \] The number \( g \) here has to be positive, because the PE is higher.

  4. ricardovg
    • 4 years ago
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    Positive, W=Force*Height=mgh and all magnitues are positive.

  5. JamesJ
    • 4 years ago
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    If it were the case that the g in these equations were negative, how is it that a mass dropped from a height of 2 meters has a higher kinetic energy, KE, when it reaches the ground than an object dropped from 1 meter? It makes no physical sense.

  6. ricardovg
    • 4 years ago
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    The force a man do to take the object higher from the surface of the earth is positive, and the force earth do is negative and equals to that of the person.

  7. ricardovg
    • 4 years ago
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    The object win potencial energy.

  8. anonymous
    • 4 years ago
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    its positive

  9. ricardovg
    • 4 years ago
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    Down negative, Up positive, Force is a vector, has direction and magnitude.

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