The magnetic field inside a solenoid of circular cross section is given by B(vector)  =  btk̂, where b = 2.1 T/ms. At time t = 0.40 μs, a proton is inside the solenoid at x = 5.0 cm, y = z = 0, and is moving with velocity v (Vector) = 4.8ĵ Mm/s. Find the electromagnetic force on the proton.