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: Moment of Inertia Constant

  1. Jun 5, 2010 #1
    1. The problem statement, all variables and given/known data
    For a little background, this lab was on energy of a rolling object. We rolled a hollow cylinder from the top of a ramp on a table and onto the floor. We are trying to experimentally derive the constant (k) found in the equation for moment of inertia.

    Variables: h = height from top of ramp to table, H = height from table to floor, x = distance ball travels from end of ramp to its landing on floor

    Make a graph of x^2 vs h. Add a trendline. Calculate k from the slope of the trendline as it corresponds to x^2 = (4Hh)/(k+1)

    My trendline equation is x^2 = 1.98h - .086

    2. Relevant equations

    I = kmr^2
    x^2 = (4Hh)/(k+1)
    We know theoretically that k=1 for a hollow cylinder

    3. The attempt at a solution
    At first I thought the slope was k but that doesn't make sense because my expected k is 1.
    I could just calculate k given my experimental measurements, but that's not what they're asking. I'm trying to relate the given equation to mx+b form but I'm drawing a blank. I don't know how to start.

    Thanks!
     
  2. jcsd
  3. Jun 5, 2010 #2

    rock.freak667

    User Avatar
    Homework Helper

    You have x2 = (4Hh)/(k+1) ⇒ x2 = (4H/(k+1)) h

    this is in the form Y=MX+C, Y=x2 and X=h. What is M?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook