Question

Part A: The sun produces 3.9 ⋅ 1033 ergs of radiant energy per second. How many ergs of radiant energy does the sun produce in 3.25 ⋅ 103 seconds? (5 points)
Part B: Which is the more reasonable measurement of the distance between the tracks on a railroad:
1.435 ⋅ 10−3 mm or 1.435 ⋅ 103 mm? Justify your answer. (5 points)

Answer 1

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Answer:

  A) 1.3×10^37 ergs

  B) 1.435×10^3 mm

Step-by-step explanation:

A) The quantity is found by multiplying the rate by the time:

  (3.9×10^33 ergs/s)×(3.25×10^3 s) = 1.2675×10^37 ergs ≈ 1.3×10^37 ergs

The least-precise contributor to the calculation has 2 significant digits, so we need to round the result to 2 significant digits.

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B) A fine human hair is more than 40×10^-3 mm in diameter, so the distance 1.435×10^-3 mm is completely unreasonable for railroad track spacing. The space between rails is closer to 1.4 meters. So 1.435×10^3 mm is a better measurement.