A brass rod with a mass of 0.300 kg slides on parallel horizontal iron rails, 0.440 m apart, and carries a current of 15.0 A. The coefficient of friction between the rod and rails is 0.300. What vertical, uniform magnetic field is needed to keep the rod moving at a constant speed

The magnitude of the magnetic field is  

Explanation:

From the question we are told that

   The mass of the rod is  

    The distance of separation is  

     The current is  

     The coefficient of friction is  

Generally for the rod the rod to continue moving at a constant speed

   The frictional force must equal to the magnetic field force so

Where  

and    

=>    

substituting values

i think if it were me i whould divide 300 dide 15

step-by-step explanation:

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.