# Sliding Bar On Rails

Can i get some help on this problem?
A conducting bar of length L = 25.6 cm and mass M = 35.0 g lies across a pair of conducting rails. The contact friction between the bar and the rails is negligible, but there is a resistor at one end with a value R = 45.0 Ohms. Initially the rod is given an initial speed of v0 = 41.0 meters per second. There is a uniform magnetic field perpendicular to the plane containing the rod and rails of magnitude B = 1.4 T.
What is the speed of the rod at time t = 23.297 s?
How far does the rod slide before coming to rest?

Related Advanced Physics Homework Help News on Phys.org
OlderDan
Homework Helper
the velocity induces an emf, the emf gives a current, and
the current gives a backward force F=ILB
How do i set it up to solve for the final velocity?

I can't figure out how to do part two either because
setting v to zero, you cannot solve for t because ln (0)
is undefined.

OlderDan
Homework Helper
the velocity induces an emf, the emf gives a current, and
the current gives a backward force F=ILB
How do i set it up to solve for the final velocity?

I can't figure out how to do part two either because
setting v to zero, you cannot solve for t because ln (0)
is undefined.
The movement of the bar changes the flux through the loop in a way that depends on the velocity. The emf and the current are related to the rate of change of the flux. The force is related to the current and the strength of the field. The rod decelerates in proportion to the force. Start writing the equations that describe these phenomena and see if you can come up with an equation for the acceleration of the rod.

which equation is the one that deals with flux and velocity, i was trying to use these ones to solve:
F=ma=ILB
I=BLV/R

OlderDan