It takes four barbarians to turn the wheel below. how many barbarians would it take if the wheel radius were doubled and the axle radius stayed the same?

a. fewer than four barbarians.
b. exactly four barbarians.
c. more than four barbarians.
d. not enough information.

The nuclear potential that binds protons and neutrons in the nucleus of an atom is often approximated by a square well. imagine a proton conned in an innite square well of length 105 nm, a typical nuclear diameter. calculate the wavelength and energy associated with the photon that is emitted when the proton undergoes a transition from the rst excited state (n 2) to the ground state (n 1). in what region of the electromagnetic spectrum does this wavelength belong?