An alert physics student stands beside the tracks as a train rolls slowly past. He notes that the frequency of the train whistle
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Answer:
The answer is below
Explanation:
The resistance of a conductor (R) is given by:
and ρ is resistivity
The length = 20cm = 0.2 m
The tube has an outer diameter of 1.1 cm (0.011 m), hence the outer area is:
A₁ = π * diameter²/4 = π * 1.1²/4 = 0.000095 m²
The tube has an inner diameter of 0.85 cm (0.0085 m), hence the inner area is:
A₂ = π * diameter²/4 = π * 0.0085²/4 = 0.0000567 m²
The conductor area = outer area - inner area = 0.000095 m² - 0.0000567 m² = 0.0000383 m²
Hence, the resistance is:
The formula for accelerational displacement is at^2/2, so we know that 3.9t^2/2 = 200, or 3.9t^2 = 400. t = 
, at = v, so 