3. Two carts, each with a mass of 2.5 kg, move toward one another. a. If the cart moving left is traveling at 10 m/s and the cart moving right is traveling at 8 m/s, what is the
magnitude and direction of the total momentum of the system?
b. What is the total momentum of the system if the two carts have the same speed?

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?