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1. The problem statement, all variables and given/known data

Suppose the rod in the figure has mass m = 0.38 kg and length 26 cm and the current through it is I = 40 A.

If the coefficient of static friction is u_{s}= 0.49, determine the minimum magnetic field B (not necessarily vertical) that will just cause the rod to slide. Give the magnitude of B.

Express your answer using two significant digits.

2. Relevant equations

F = IBd

F = u_{s}F_{N}

3. The attempt at a solution

Since its just "just beginning to move", I know that the two forces are equal to eachother.

So:

IBd = u_{s}F_{N}

IBd = u_{s}mg

which means that:

B = (u_{s}mg) / Id

I plug in the values (after converting them to standard SI units), and I get .175 T. To two significant figures would be .18. But thats not right, I also tried .17, not that either, .2 was also wrong. I don't know what I'm doing wrong.

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# Homework Help: Give the magnitude of the magnetic field that will.

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