2 meters per second (2 m/s)
This is because you divide distance by time
To solve the problem, start by applying the concepts related to current in an RL circuit. The current is defined exponentially and using Ohm's law we can put the initial current in terms of the voltage and resistance. Consecutively with the calculated time constant we can find the respective inductance. For the second part we will apply the electrical potential energy connectors to find the amount of stored energy.
PART A)





Inductance can be defined then,



PART B) Now the energy is given under the terms:



Therefore the energy stored in the coil at this same moment is 0.0002727J
distance(d) = speed(s) × time (t)
= 22.3 × 8.5
= 189.55m
The magnetic field is holding onto the nail that’s all I got