For this problem there are 2 separate cases; 'a' with the 30 lb weight and 'b' with a 30 lb downward force. Does it make sense for alpha_a > alpha_b in magnitude? If so why?(using intuition rather than math...I know we talked about this in class)
(Click on this link for a copy of the solution for this problem, as added by CMK.)
1 comment:
In (a), the block effectively adds to the moment of the inertia of the disk.
To see this, look at the next-to-last equation on the problem solution (I posted a link to this on your original post). In that equation, you see that the block adds the term of m_A*r^2 to the moment of inertia of the disk in the denominator of the equation for alpha.
In the last equation in that solution (which is for part (b)) this added inertia term is not present.
In summary, the presence of the blocks makes the system appear to have a larger mass moment of inertia, and as a result, it will result in a smaller angular acceleration in (a) than in (b) for the same net torque.
Let us know if this does not help.
Post a Comment