Lab: Moment of Inertia

Lab: Moment of Inertia

Purpose: Calculate the moment of inertia and the frictional torque of a disk and apply the value to predict the motion of the system of the disk and the cart.

Equipment:
A large metal disk, a video capture, a cart and a track.

Experiment:
1. Set the video capture and the metal disk.
2. Measure the radii of the small disks and the large disk, and read the mass of the disks.
3. Calculate the mass of each disk by volume and calculate the moment of inertia by the equation I=1/2 m r^2.
4. Spin the apparatus, use video capture to determine its angular acceleration as it slows down.
5. Calculate the torque of friction by the equation of torque=inertia times angular acceleration.
6. Calculate the acceleration of the system of the cart and the disk.
7. Predict the time it needs to travel 1 meter.
8. Do the experiment for three times and calculate the percent error.

Calculation:

Conclusion:
Through our calculation, we get the theoretical time is 7.83s. Through the experiment, we get the average time that the cart travel 1 meter is 7.84s. The percent error is 0.128%, which is lower than 4%。