READ ALSO : Homework: Chapter 3 What forms of energy are used in the following sports: a. Surfing b. Nascar racing c. Hang Gliding d. Skiing e. Golf f. Mountain climbing Would it be energy efficient to use a solar water heating system in Alaska? Why or why not? What would be a more efficient energy choice to heat water in cold climates? 3. Is it possible to use alternative energy sources to meet the current energy demands of the United States? What are some of the environmental costs for different forms of alternative energy sources? (Hint: Wind turbines kill birds and bats.) 4. How do “warm-blooded” animals warm their blood? What form of energy do “cold-blooded” animals use to warm their blood and bodies? 5. Does the total amount of energy in an isolated system change over time? Why or why not? 6. If you eat 500 calories per day (roughly one large order of fries) above your energy needs, how long will it take to gain 20 pounds? How long would you have to walk (assuming you burned 80 calories per mile walked) to burn off those 20 pounds? 7. How much work against gravity do you perform when you walk up a flight of stairs five meters high (assuming that your body mass is 75 kilograms)? Compare this work to the energy done by a 100-watt light-bulb in an hour (60 minutes). 8. Which has more gravitational potential energy: a 200-kilogram boulder 1 meter off of the ground, a 50-kilogram boulder 4-meters off the ground, or a 1-kilogram rock 200 meters off the ground? Which of these can do the most work if all of the potential energy was converted to kinetic energy? 9. Compared a car (mass of 2000 kg) moving at 10 miles per hour, how much kinetic energy (in Joules) does that same car have when it moves at 20 miles per hour? At 50 miles per hour? 75 miles per hour? (Hint: you will need to convert to miles per hour to meters per second). 10. Using your results from question 9, create a graph of those results. What does your graph suggest to you about the difficulty of stopping a car as its speed increases? *In MS Word, you can create a graph by going through Insert > Chart > x-y scatter and then inputting your velocity (m/s) and energy (J). Homework: Chapter 4 What kind of heat transfer warms your hands when you hold them by a fire? Why is it easier to demolish a building than it was to build it? Why is it more efficient to burn fossil fuels to supply heat than to generate electricity? Describe at least three examples of heat transfer that occur when you go for a long walk on a cold day. In each instance, state whether the heat transfer is by conduction, convection, or radiation. Where does the energy come from? Where does it end up? Why does the handle of a metal spoon heat up rapidly when placed in a cup of hot coffee, but a plastic spoon does not? What is specific heat capacity? Which heats more quickly, a kilogram of water or a kilogram of copper. Why? Calculate the maximum possible efficiency of a power plant that burns natural gas at a temperature of 600 K, with low-temperature surroundings of 300 K. How much more efficient would the plant be if it were built in the Artic where the low-temperature reservoir is at 250 K? Why don’t we build all power plants in the Artic? Calculate how much energy would be needed to raise the temperature of 10 kilograms of water from 273 to 373 K. What is the temperature of the water in degrees Fahrenheit and Celsius after the water is heated? What state (solid, liquid or gas) will the water be in? You have a collection of six numbered balls; 1 through 3 are blue and 4 through 6 are green. How many different arrangements of these balls in a line are possible? What percentage of those arrangements have three blue balls followed by three green balls? 10. The temperature in Washington, DC is 80oF on Monday, 70oF on Tuesday and Wednesday, 650F on Thursday through Saturday, and 75oF on Sunday. What is the average temperature for that week in both Kelvin and Celsius? Graph your data and results in both a line and bar (so two separate graphs) format. Which graph better represents your data?
