midterm 2

midterm 2 - muffins can he burn if he climbs up the Grouse...

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1. An egg (0.05 kg) is just about to hit a dorm window at a speed of 20 m/s (44 mph)? What units can we use to describe the kinetic energy of the egg? Circle all that can be used. A) Calories only B) Joules only C) kg m^2/s^2 only D) kilowatt-hours only 2. How much potential energy does a 70 kg hiker gain by climbing up the Grouse Grind (elevation gain 800 m). 3. Both solar energy and radioactivity of the earth’s crust deliver a lot of energy to the Earth, which all ends as heat. So why doesn't planet Earth keep getting hotter and hotter? A) The oceans keep us cool B) The amount of heat is too small to notice C) We are heating up, that's global warming D) The energy gets radiated out into space E) The powerful lobby of the cloth manufacturers and fashion designers prevents this from happening 4. A hiker 1.8 m tall weighing 70 kg noticed that he needs an additional food intake of 260 kcal if he walks for 5.8 km instead of sitting down and watching TV. How many
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Unformatted text preview: muffins can he burn if he climbs up the Grouse Grind (elevation 800 m, trail length 2.9 km) compared to when he is watching TV? The caloric intake of the muffin is 400 kcal. Humans convert the chemical energy of the food to mechanical energy with 20% efficiency. 5. Two surveyors are working in the Canadian arctic when a snowstorm blows in. To help survive the cold they build themselves an Igloo. (An Igloo is a shelter constructed from blocks of snow, generally in the form of a dome. Although igloos are usually associated with all Inuit people, they were predominantly constructed by people of Canada's Central Arctic and Greenland’s Thule area.) The total wall and roof area of the Igloo is 25 m 2 and the average R value is 25. What is the temperature inside while it is -30ºC outside? State clearly all the assumptions that you made while solving this problem. Notice: Make sure that you express R value in the appropriate units....
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This note was uploaded on 11/03/2009 for the course PHYS100 100 taught by Professor Lioudmila during the Spring '09 term at UBC.

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