I think it might be A. I’m sorry if I’m wrong
Answer with Explanation:
We are given that
Magnetic field,B=

Length of wire,l=15 m
Current,I=19 A
a.We have to find the magnitude of magnetic force and direction of magnetic force.
Magnetic force,F=
Using the formula


Direction=

15 degree above the horizontal in the northward direction.
¡Hellow!
For this problem, first, lets convert the seconds in hours:
5,4x10³
5400
h = sec / 3600
h = 5400 s / 3600
h = 1,5
Let's recabe information:
d (Distance) = 386 km
t (Time) = 1,5 h
v (Velocity) = ?
For calculate velocity, let's applicate formula:

Reeplace according we information:
386 km = v * 1,5 h
v = 386 km / 1,5 h
v = 257,33 km/h
The velocity of the train is of <u>257,33 kilometers for hour.</u>
<u></u>
Extra:
For convert km/h to m/s, we divide the velocity of km/h for 3,6:
m/s = km/h / 3,6
Let's reeplace:
m/s = 257,33 km/h / 3,6
m/s = 71,48
¿Good Luck?