In: Physics
A grandfather clock has a pendulum that consists of a thin brass
disk of radius 36 cm and mass 1.8 kg that is attached to a long,
thin rod of negligible mass. The pendulum swings freely about an
axis perpendicular to the rod and through the end of the rod
opposite the disk. The pendulum should be designed so that its
period is 2 s for small oscillations when the gravitational
acceleration is 9.8 m/s2.
(a) What should the length of the rod be?
(b) If this were a simple pendulum, what would the rod's length
have to be?
[Don't forget to account for the physical size of the disk.]
(c) What would the percent error be in using the equations for a
simple pendulum?
The pendulum oscillates about the pivot of the rod.If we consider dimension of the disc,it rotates about the pivot,about which its moment of inertia is calculated using parallel axis theorem. In simple pendulum-case,the disc is translating in the circular path.