Can you check this? Samantha swam upstream for some distance in one hour. She then swam downstream the same river for the same d
istance in only 12 minutes. If the river flows at 4 mph, how fast can Samantha swim in still water?
2 answers:
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Answer:
Explanation:
The resistance of a wire is given by:
where
is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire
1) The first wire has length L and cross-sectional area A. So, its resistance is:
2) The second wire has length twice the first one: 2L, and same thickness, A. So its resistance is
3) The third wire has length L (as the first one), but twice cross sectional area, 2A. So, its resistance is
By comparing the three expressions, we find
So, this is the ranking of the wire from most current (least resistance) to least current (most resistance).