StudyGuide1 - OWL Homework 1 Solution Question: There are...

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OWL Homework 1 Solution Question: There are 1.61 kilometers in a mile. How many kilometers are there in 10 miles? Answer: 1.61 x 10 = 16.1 km. Question: There are 5.878 x 1012 miles in a light year. How many miles are there in 13 light-years? Answer: 13 x 5.878e12 = 7.64e13 miles. Question: Highway speed is about 100 km/hour. Suppose you could drive a car at this speed to the planet Venus when it is 0.28 AU away from us. How many hours would it take to get there? (1 AU is 150 million kilometers.) Answer: Distance: 0.28 AU = 0.28 x 150e6 km = 4.2e7 km. (distance)/(speed) = 4.2e7 ÷ 100 = 4.2e5 hours Question: The radius of the Earth is about 6,400 km. If you say "hello" to your friend Joe on the other side of the Earth via a satellite phone, how long will that message take to reach Joe if the message travels at the speed of light? Answer: Distance: π x r or 3.14 x 6400 km = 20096 km. Speed of light: 300,000 km/second. (distance)/(speed) = 20096 km ÷ 3e5 km/second = 0.067 second. Question: Your friend Joe is now sitting on the Moon. If you say "hello" to Joe using a radio from Houston, how long will that message take to reach Joe if the message travels at the speed of light? Answer: Distance: 384.4e3 km. Speed of light is 3e5 km/second. (distance)/(speed) = 384.4e3 km ÷ 3e5 km/second = 1.3 second. Question: Now Joe is inside a spaceship orbiting the Sun. If you say "hello" to Joe using a radio from Houston, how long will that message take to reach Joe if the message travels at the speed of light? Answer: Distance 1.5e8 km. Speed of light is about 3e5 km/second. (distance)/(speed) = 1.5e8 km ÷ 3e5 km/second = 500 seconds. Question: If Polaris is 40 degrees from your zenith, what is your latitude? Answer: Latitude (LA) and the zenith angle (ZA) of Polaris are related as "ZA = 90 - LA" or "LA = 90 - ZA". So at the North Pole, Polaris is directly overhead (ZA = 0), and your latitude LA = 90 - 0 = 90 degrees. If ZA = 40, then your LA = 90 - 40 = 50 degrees. OWL Homework 2 Solution Question: The angular size of the Moon is about 30 arcmin. If it were 8.19 times as far away as it is now, how big would its angular diameter be?
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Answer: 30 ÷ 8.19 = 3.66 arcmin Question: The speed of light is 300,000 km/sec. How longs does it take light to travel 50 thousand km? Answer: 50,000 ÷ 300,000 = .667 seconds Question: The speed of light is 300,000 km/sec. How long would it take for a flashlight beam you shine at Venus to reach it when it is at its closest, about 41 million kilometers away from us? Express your answer in minutes. Answer: 41,000,000 ÷ 300,000 = 136.667 136.667 ÷ 60 = 2.278 minutes Question: Suppose you measure 5 Joules for the kinetic energy of a housefly. The housefly speeds up to 3 times faster than it was moving before. How many Joules of kinetic energy does the housefly have now? Answer:
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This note was uploaded on 04/08/2008 for the course ASTRON 100 taught by Professor Minyun during the Spring '08 term at UMass (Amherst).

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StudyGuide1 - OWL Homework 1 Solution Question: There are...

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