In order to make the rod of Fig. 21-11a move to the right at speed v, you

Question:

In order to make the rod of Fig. 21-11a move to the right at speed v, you need to apply an external force on the rod to the right.
(a) Explain and determine the magnitude of the required force.
(b) What external power is needed to move the rod? (Do not confuse this external force on the rod with the upward force on the electrons shown in Fig. 21-11b.)