A 20-cm-long, zero-resistance wire is pulled outward, on zero-resistance rails,

Question

A 20-cm-long, zero-resistance wire is pulled outward, on zero-resistance rails, at a steady speed of 1.0 m/s in a 0.10T magnetic field (See the figure). On the opposite side, a 1.0? carbon resistor completes the circuit by connecting the two rails. The mass of the resistor is 75 mg.

What is the induced current in the circuit?

_______ A

How much force is needed to pull the wire at this speed?

________ N

How much does the temperature of the carbon increase if the wire is pulled for 10s? The specific heat of carbon is 710J/kg??C.

Delta T = _______?C

Below is the picture

http://session.masteringphysics.com/problemAsset/1169624/3/jfk.Figure.25.P57.jpg

Explanation / Answer

acc is 0 so F=BIL
also current I is BVL/R
I=.020A
F=.1*.020*.20=4.0*10^-4N
power= I^2*R
=4.0*10^-4J/sec
so for 10 sec 4.0*10^-3J
energy=mass*s*change in temp
=75*10^-3*710*T
T comes out to be 7.5117*10^-5

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