Moment of Inertia of the disk

  • #1

Homework Statement

A uniform disk of radius 0.12 m is mounted on a frictionless, horizontal axis. A light cord wrapped around the disk supports a 1 kg object, as shown in the figure from rest the object falls with a downward acceleration of 2.3 m/s^2.The acceleration of gravity is 9.8 m/s^2 When released What is the moment of inertia of the disk? in units of kg m^2

Homework Equations

Moment of Inertia of a disk by itself= 1/2MR^2
I= Torque/Angular Acceleration

The Attempt at a Solution

1/2*(M)*(.12^2) = I

If there is downward acceleration of 2.3 m/s^2 is that added to the 9.8 m/s^2 from gravity? 12.1 m/s^2

Im having a hard time knowing where to start with how this 1kg object affects the moment of inertia of the disk, and how I find M in the disk.


  • MomentOfInertia.doc
    29 KB · Views: 208

Answers and Replies

  • #2
You'll need to separately analyze the forces on the hanging mass and on the disk.

Start with the hanging mass. Apply Newton's 2nd law to find the tension in the cord.

Suggested for: Moment of Inertia of the disk