Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Density at certain temps

  1. Oct 8, 2004 #1
    lets say for example the density for gasoline is 730 kg/m^3 at 0 degree Celsisus

    Will the density be different for at a diff temperature, or will it always remain constant?

    If it is different, how would you calculate it? thanks
     
  2. jcsd
  3. Oct 9, 2004 #2
    Density is mass per unit volume (well, mass density anyways)

    So heating or cooling would change the density beucase the volume that the substance would change. There are a number of different ways to find the change in volume of the substance...depending on what form it is in, etc.
     
  4. Oct 9, 2004 #3
    well for my homework question, it gives the avg coefficient of volume expansion. and from there on i have no idea how to calculate the density of gasoline at a diff temp.
     
  5. Oct 9, 2004 #4
    use the following equation:

    [tex]\Delta V = \delta*V*\Delta T[/tex]

    Where [tex]\Delta V[/tex] is the change in volume, [tex]\delta[/tex] is the coefficient of volume expansion, V is the current volume, and [tex]\Delta T[/tex] is the change in temp

    Edit: Changed symbols to Latex
     
    Last edited: Oct 9, 2004
  6. Oct 9, 2004 #5
    i know, but once u find the change in volume, how can u relate it to finding density at a certain temp?

    for example, lets say density of gasoline is 730 kg/m^3 at 0 degrees

    what will the density be at 20 degrees?

    a gallon of gasoline occupies .00380 m^3 and the avg coefficient of volume expansion is 9.6e-4

    So plugging it into the equation, i got a change of volume of 7.296e-5, with final volume being .00387296...now from here how would i be able to find the new density at the new temp?
     
  7. Oct 9, 2004 #6
    well, remember, mass density = mass / volume

    you know the new volume...and you know the mass (hint: use the original density and the original volume to find the mass)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook