Question1

A frictionless pulley has the form of a uniform solid disk of mass 4.00 and radius 23.0. A 1.80 stone is attached to a very light wire that is wrapped around the rim of the pulley, and stone is released from rest. As it falls down, the wire unwinds without stretching or slipping, causing the pulley to rotate. How far have to the stone fall so that the pulley has 3.40 of kinetic energy?

Question2

The potential energy of interaction between atoms in an ionic solid as a function of parting distance is given by V(r) = -A/r + Br^n, where A, B, and n are constants.

(a) Obtain a relation between the equilibrium lattice distance a and A,B, and n.

(b) The force constant between atoms is given by Ks = (d^2V/dr^2)r=0. If Young's modulus (in units of force/area) is basically given by Ks/a, explain that it varies as a^-4 in ionic solids.