A Circuit Is Pulled with a 21-N Force Toward the Right

Multiple Choice

A circuit is pulled with a 21-N force toward the right to maintain a constant speed v.At the instant shown,the loop is partially in and partially out of a uniform magnetic field that is directed into the paper.As the circuit moves,a 4.0-A current flows through a 6.0- resistor.

-What is the magnitude of v?

A) 1.5 m/s
B) 4.6 m/s
C) 6.4 m/s
D) 7.8 m/s
E) 9.0 m/s