SOLUTION: A solid copper cylindrical bar 10cm long and 3cm in diameter is drawn out into a wire 1mm in diameter. a) How long is the wire. b) How long would it be if the diameter was ½mm?

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Question 1205010: A solid copper cylindrical bar 10cm long and 3cm in diameter is drawn out into a wire 1mm in diameter.
a) How long is the wire.
b) How long would it be if the diameter was ½mm?
Answer by ikleyn(52835)   (Show Source): You can put this solution on YOUR website!
.
A solid copper cylindrical bar 10cm long and 3cm in diameter is drawn out into a wire 1mm in diameter.
a) How long is the wire.
b) How long would it be if the diameter was ½mm?
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The diameter of the cross-section of the wire is   the diameter of the original cylinder.

Hence, the area of the cross section of the wire is   =  of the area of cross-section of the cylinder.


The volume remains the same ---> HENCE, the length of the wire is 900 times 10 cm, or 9000 cm, which is 90 meters.    ANSWER

Part (a) is solved mentally.

Solve part (b) in the same way.

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The lesson to learn from my solution is the Law of mass conservation.



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