1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Lower inertia means it moves faster, right?

  1. Nov 13, 2012 #1
    I was working out a conceptual question that asks: if a disk and a hoop of equal mass and radius start from the top of a ramp, are realeased at the same time, and roll without slipping, which one reaches the bottom of the ramp first?

    Disk: I = 1/2(m)(r^2)

    Hoop: I = mr^2

    So the inertia of the disk ends up being lower. Lower inertia means the disk moves faster, right?
     
  2. jcsd
  3. Nov 13, 2012 #2

    lewando

    User Avatar
    Gold Member

    "It accelerates faster" would be more correct. Looking at τ=Iα, for the the two cases with equal torque (τ) applied, if I (moment of inertia) was smaller, then α, (angular acceleration) would have to be larger.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook