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

Finding moment of inertia

  1. Jan 2, 2010 #1
    a uniform solid block has mass 0.172 kg and edge lengths a=3.5cm, b=8.4cm, and c=1.4cm (c is the height of the rectangular solid).Calculate its rotational inertia about an axis through one corner and perpendicular to the large faces.

    i know the formula is integral of r^2 dm, but i have no idea what to do here. i have r^2 = a^2 + b^2. but i don't know how what to substitute for dm.
  2. jcsd
  3. Jan 2, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi demonelite123! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    If r2 = x2 + y2, then dm = density times dxdydz (or, if you're only integrating over x and y, then dm = hdxdy). :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook