<span>Velocity is a vector and it has both speed and direction. It takes a force to change direction just as it does to change speed</span>. In order to have a constant velocity the object must maintain a constant direction and speed. Hope this answers the questions. Have a nice day.
To solve the problem it is necessary to apply the concepts related to Force of Friction and Tension between the two bodies.
In this way,
The total mass of the cars would be,


Therefore the friction force at 29Km / h would be,




In this way the tension exerts between first car and locomotive is,



Therefore the tension in the coupling between the car and the locomotive is 
Answer:
a) B=0.008 T
b) +z direction
Explanation:
<u>solution:</u>
a) The magnetic force:
F=i*l*B
Solve for B:
B=0.008 T
b) According to the left hand rule, the magnetic field is in the +z direction