First this Q might be trivial thus apologies. Consider two bar electromagnets that can simulate bar magnets M1 and M2, placed end to end at distance D apart (North Pole of M1 facing South Pole of M2). Magnet M1 is 'fixed' to a base. Assuming both electromagnets have the Current I1 and Voltage V1. The magnets will attract each other and M2 will travel the distance D in some time T1. How will the the Net effective force of attraction (considering the effects of Back EMF) thus time taken, change with change in: Current Voltage Important: We have to keep in mind the 'Back EMF' generated due to motion, that negates this attractive motion and how it changes with Current and Voltage (the part which I am unsure of). Q1. Is there a simple formula for the Net Force (and time taken) w.r.t. changes in the above 3.? Q2. In other words how does changing the parameters, affects the time M2 will take to travel distance D?