Q. The density of mobile electrons in copper metal is 8.4 1028 m-3. Suppose that i = 9.0 1018 electrons/s are drifting through a copper wire. (This is a typical value for a simple circuit.) The diameter of the wire is 2.0 mm. In this case, about how many minutes would it take for a single electron in the electron sea to drift from one end to the other end of a wire 38 cm long?
Q. A 50.0 g ball is fired horizontally with initial speed v_0 toward a 110 g ball that is hanging motionless from a 1.10 m-long string. The balls undergo a head-on, perfectly elastic collision, after which the 110 g ball swings out to a maximum angle theta_max = 52.0^circ.