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Homework Help: Need help solving these MCQ's

  1. May 4, 2010 #1
    1. 3) Flatten a spherical meat ball and you increase its
    A) Volume
    B) Surface area
    C )Both of these
    D) Neither of these

    4) Surface tension of liquids
    a) Result from a thin molecular membrane on the liquid surface.
    b) Increases when wetting agents are added
    c) Is the reason a steel ship will float
    d) Decreases as the liquid temperature increase
    e) Is about the same for all liquids

    6) The cooling effect inside a refrigerator is produced by
    a) Vaporizing the refrigeration liquid
    b) Proper insulation
    c) An electric motor that converts electrical energy into internal energy
    d) Compressing the refrigeration gas into a liquid.
    e) None of these.

    9) If you use 10j of work to push charge into an electric field and then release the charge, as it files past its starting position, its kinetic energy is
    a) Less than 10 J
    b) More than 10 J
    c) 10 J

    16)The wavelengths of sound that carry farther in air are relatively
    a) Along
    b) Short
    c) No difference.

    17) Which involves the larger number of calories?

    a) The condensation of 1 gram of steam at 100 degree Celsius to 100 degree Celsius water
    b) The change of state of 1 gram of 100 – degree- Celsius water to 1 gram of ice at absolute zero
    c) both involve the same number of calories

    3. The attempt at a solution

    plz provide answers with explanation. thanks
  2. jcsd
  3. May 4, 2010 #2
    3) i think surface area will increase as the voulme will decrease.
    4) i am confused between option a and d as if we decrese the temperature the surface tension appears to increase
    6) i think option a. as it takes the heat from the food and vaporizes the frezing material...
    9) i think it should be 10j , the same as much energy we put to move it from this position.
    16) this confuses me a bit.. if a wave has high frequency it has high energy, E=h*f right? but it also loses more energy as it propogates.. so high frequency waves( short wavelength) cannot propogate long distances.. so that makes the correct option a) long wavelengths wave can travel farther, am i doing right?

    17) i have no idea where to start from..:S
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