- #1
discoverer02
- 138
- 1
I'm having trouble with the following problem:
A bar of mass m, length d, and resistance R slides without friction on parallel rails. A battery that maintains a constant emf E is connected between the rails, and a constant magnetic field B is directed perpendicular to the plane of the page and out of the page. If the bar starts from rest, show that at time t it moves with a speed:
v = E/Bd(1 - e^{(-B^2)(d^2)t/(mR)})
in diagram the bar is on the left and the battery is set up on the right so the current runs counterclockwise through the circuit.
The first thing that I'm confused about is the force that sets this in motion. From the problem statement and the diagram, the magnetic field is caused by the current running through the wire, so unless some force is applied to the bar it's not going to move.
I begin trying to solve the problem by working with the following equation:
Sum of the Forces in the x direction = -IdB + F_applied = ma
F_applied = mass x some initial acceleration?
Is this the correct approach. I've tried many and I'm got getting the correct answer.
Can anyone nudge me in the right direction?
Thanks
A bar of mass m, length d, and resistance R slides without friction on parallel rails. A battery that maintains a constant emf E is connected between the rails, and a constant magnetic field B is directed perpendicular to the plane of the page and out of the page. If the bar starts from rest, show that at time t it moves with a speed:
v = E/Bd(1 - e^{(-B^2)(d^2)t/(mR)})
in diagram the bar is on the left and the battery is set up on the right so the current runs counterclockwise through the circuit.
The first thing that I'm confused about is the force that sets this in motion. From the problem statement and the diagram, the magnetic field is caused by the current running through the wire, so unless some force is applied to the bar it's not going to move.
I begin trying to solve the problem by working with the following equation:
Sum of the Forces in the x direction = -IdB + F_applied = ma
F_applied = mass x some initial acceleration?
Is this the correct approach. I've tried many and I'm got getting the correct answer.
Can anyone nudge me in the right direction?
Thanks