What was Eratosthenes's mathematical contribution to the history of astronomy, even though it was incorrect?
a. He calculated the diameter of Earth by what he learned from travelers' itineraries
b. He estimated Earth's revolution rate by measuring the length of shadows casted on the surface.
c. He determined that all the planets orbited Earth every 24 hrs.
d. He attempted to calculate Earth's radius by utilizing the position of sunlight.
e. He believed all of nature was underlain by musical principles.
d
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A group of 1.0-?F, 2.0-?F, and 3.0-?F capacitors is connected in parallel across a 24-V potential difference (a battery). How much energy is stored in this three-capacitor combination when the capacitors are fully charged?
A) 1.7 mJ B) 2.1 mJ C) 4.8 mJ D) 7.1 mJ
A stream of electrons passes through a velocity filter where the crossed magnetic and electric fields are 0.020 T and 5.00 × 10^4 V/m, respectively. Find the kinetic energy (in electron volts) of the electrons passing through the filter. [1 eV = 1.60 × 10^?19 J]
A refrigerator uses 100 W of electric power and discards 600 W of thermal power into the kitchen. What is its coefficient of performance?
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