A thin, 53.0cm long metal bar with mass 790g rests on, but is not attached to, t

Question

A thin, 53.0cm long metal bar with mass 790g rests on, but is not attached to, two metallic supports in a uniform magnetic field with a magnitude of 0.440T , as shown in the figure. A battery and a resistor of resistance 27.0?(ohm) are connected in series to the supports.

Part A

What is the largest voltage the battery can have without breaking the circuit at the supports?

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Correct

Significant Figures Feedback: Your answer 896.37 V was either rounded differently or used a different number of significant figures than required for this part.

Part B

The battery voltage has the maximum value calculated in part (a). If the resistor suddenly gets partially short-circuited, decreasing its resistance to 2.80?(ohm) , find the initial acceleration of the bar.

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Explanation / Answer

Here ,

A)

for balancing the force ,

Fm = Fg

B*I*L = m*g

0.44 * V * 0.53/27 = 0.790 * 9.8

V = 896 V

B)

Now, for resistance decreaing to 2.8 Ohm

using second law of motion

Fnet = m*a

a * 0.79 = (0.44 * 896 * 0.53/2.8 - 0.79 * 9.8)

a = 84.7 m/s^2

the inital acceleration is 84.7 m/s^2

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