What is the terminal speed at which the bar falls? Assume the bar remains horizontal and in contact with the r?

A 60 horizontal metal bar, 12 long, is free to slide up and down between two tall, vertical metal rods. A 5.0脳10鈭? magnetic field is directed perpendicular to the plane of the rods. The bar is raised to near the top of the rods, and a 1.0 resistor is connected across the two rods at the top. Then the bar is dropped.|||F = mg = ILB ==%26gt; I = mg/(LB)


Energy = Fv = mgv = I^2R ==%26gt;


v = I^2R/(mg) = (mg/(LB))^2R/mg = mgR/(LB)^2





B = 0.05 T, g = 9.81 m/s^2


Since you didn't provide any units, I can only guess at the rest.


m = 60 g (0.06 kg), L = 12 cm (0.12 m), R = 1 ohm


v = 0.06*9.81*1/(0.12*0.05)^2 = 16350 m/s|||Surely no lab experiment would use such values; there's not enough height to reach terminal speed. Maybe R = 1 milliohm?


On the other hand, the question did say the vertical rods were tall. Hopefully that means 13625 km. :o)


And a correction: "Energy =" should be "Power ="; no effect on answer.

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|||Is my formula bad? The check results confirm the answer:


V = vLB = 98.1 V


I = V/R = 98.1 A


F = ILB = 0.5886 N


mg = .06*9.81 = 0.5886 N

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