What Are the Equations of Motion for a Disc on a Rough Surface?

confused89
Messages
1
Reaction score
0

Homework Statement



A thin disc if mass m, centre of mass offset from centre by h (horizontally right in diagram), and radius r rests on a rough horizonal surface. It is originally at rest and then released. No slip occurs between disc and horizontal surface.

Write the equations of motions of the disc.
How many degrees of freedom?
Write the kinematic constraint equations required to solve the equations of motion.

Show that frictional force acting on the disc is F=((m^2)rh(g-h(alpha)))/(I+mr^2)
where I = moment of inertia of disc about axis through the centre of mass, normal to the disc.

Homework Equations


The Attempt at a Solution



just not really sure where to start at all.

its for an exam not homework but I really need help. thanks
 
Last edited:
Physics news on Phys.org
confused89 said:
centre of mass offset from centre by h (horizontally right in diagram)

please provide a diagram to make it clear.
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top