you know the size of the disk, and the material (aluminum)
calculate the volume and look up the density
Hi, the following is a problem that concerns angular momentum:
Modern hard drives spin very fast! The part that holds the data is a disk called the platter. Assume an aluminum platter that is 3.5in. in diameter, 1mm
thick, and spinning at 5400 rpm. Treat the platter as a solid disk - don't worry about the hole in the middle. What is the angular momentum in kg m/s^2?
As far as I'm awware, the equation for the moment of inertia of such an object is I=mr^2/2. However, I don't know the mass of the disk so I'm not sure how to solve the problem.
Thank you in advance.
2 answers
I have already calculated the mass using volume multiplied by density and the resulting answer was incorrect. However, I just realised that I had forgotten to convert the mass from grams to kilograms. Thanks for your help.