- #1
tomrja
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Homework Statement
A copper rod of mass 0.6 kg rests on two rails 1.3 m apart and carries a current of 31 A from one rail to the other. The coefficient of static friction is 0.3. What is the magnitude of the least magnetic field that would cause the bar to slide?
Homework Equations
F= ILxB
F=ma
f=(Fn)(u) where f is the frictional force, Fn is the normal force, and u is mu.
The Attempt at a Solution
I set up a free body diagram and found the equation: F-(Fn)(u)=ma. In the y direction Fn=mg=(0.6)(9.8)= 5.88N. Then I plugged that into my first equation for the x direction and got F= 0.6a + 5.88. I know that F=ILB, so I plugged that in and solved for B: B= (.6a + 1.764)/40.3. Am I on the right track? If I am then where do I get the acceleration of the copper rod from? Thanks