### Astronomy

Show your work for all questions. An answer without an explanation will not receive credit. 1. Here is some practice on conversion of units and scientific notation. Show your work – in scientific notation! – for each. a. The US imports about 12 million barrels of petroleum per day (about half of our usage). At the current cost of crude oil of $95 per barrel, how much money are we sending overseas per year per each of the 300 million people in the US to buy oil? b. Estimate how long it would take you to drive to the Sun, which is 1 AU = 1.5x1011 m away. Assume there is a nice highway to drive on, with a speed limit of 70 miles per hour. How many meals would you have to pack if you wanted to drive round-trip? c. The New Horizons spacecraft is headed to Pluto, which is about 35 AU away from Earth. It was launched in January 2006 and is expected to pass Pluto in July 2015. How fast – in meters per second, and in miles per hour – is the average speed of the New Horizons spacecraft on this voyage? 2. You are an adventurous medieval explorer who travels from Madrid to London, which is a distance of 1100 km almost due north. a. You notice that the star Algol, which passes directly overhead (the “zenith”) in Madrid, only gets to within 10 degrees of the zenith (south of zenith) when you are in London. If you are a flat-Earth advocate, you conclude that Algol must be how far away from Earth? (draw a picture!) b. You also notice that Polaris shifts from being 49 degrees north of zenith to 39 degrees from zenith during this journey. Is Polaris the same distance from the flat Earth as Algol, in the flat-Earth scenario? (somewhat tricky algebra/trigonometry required here) 3. Suppose you had a watch that always told you the local solar time. How fast (km per hour or miles per hour) would you have to run around the equator to make the watch stand still? Which direction would you be running?

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