How Fast is the Circuit Moving in a Magnetic Field?

[stephidjadi]

A circuit is pulled with a 16-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 6.0-A current flows through a 4.0- resistor.

What is the magnitude of v?
(a) 1.5 m/s (c) 6.4 m/s (e) 12 m/s
(b) 3.0 m/s (d) 9.0 m/s

the answer is (d) but i don't understand why

 

[Klockan3]

V.F=Effect=ampere*volt*=resistance*ampere^2

Put in numbers
v*16N=4ohm*36A^2
v=9m/s