PHY 101 Week 3 Learning Team Assignment Textbook Exercises

PHY 101 Week 3 Learning Team Assignment Textbook Exercises Recent

(Chapter 15)

Problem 2: Suppose that a brass rod 1.0 m long expands 0.5 cm when its temperature is increased a certain amount. By how much will a brass rod 100 m long expand with the same change of temperature (Hewitt, 2010, p. 283)?

Problem 4: Consider a 40,000-km steel pipe that forms a ring to fit snugly all around the circumference of the Earth. Suppose people along its length breathe on it so as to raise its temperature 1⁰C. The pipe gets longer. It also is no longer snug. How high does it stand above ground level? (To simplify, consider only the expansion of its radial distance from the center of Earth, and apply the geometry formula that relates circumference C and radius r, C =2πr. The result is surprising!) (Hewitt, 2010, p. 283)

(Chapter 16)

Problem 2: Radioactive decay of granite and other rocks in Earth’s interior provides sufficient energy to keep the interior molten, to heat lava, and to provide warmth to natural hot springs. This is due to the average release of about 0.03 J per kilogram each year. Show that a 500°C increase in temperature for a thermally insulated chunk of granite takes about 13.3 million years. (Assume that the specific heat capacity c of granite is 800 J/kg•C⁰. Use the equation) Q= cm Δ T.) (Hewitt, 2010, p.299)

Problem 4: At a certain location, the solar power per unit area reaching Earth’s surface is 200 W/m², averaged over a 24-hour day. If the average power requirement in your home is 3 kW and you can convert solar power to electric power with 10% efficiency, how large a collector area will you need to meet all your household energy requirements from solar energy (Will a collector fit in your yard or on your roof?) (Hewitt, 2010, p. 299)?

(Chapter 17)

Exercise 2: You can determine wind direction by wetting your finger and holding it up in the air. Explain (Hewitt, 2010, p. 312).

Exercise 4: Why is sweating an efficient mechanism for cooling off on a hot day (Hewitt, 2010, p. 312)?

Exercise 6: Can you give two reasons why pouring a cup of hot coffee into a saucer results in faster cooling (Hewitt, 2010, p. 312)?

Exercise 16: Why are icebergs often surrounded by fog (Hewitt, 2010, p. 312)?

Exercise 28: Place a jar of water on a small stand within a saucepan of water so that the bottom of the jar is held above the bottom of the pan. When the pan is placed on a stove, the water in the pan will boil, but not the water in the jar. Why (Hewitt, 2010, p. 313)?

(Chapter 18)

Exercise 16: What is the ultimate source of energy in a hydroelectric power plant (Hewitt, 2010, p. 330)?

Exercise 40: Why do we say a substance in a liquid phase is more 3 tedisordered than the same substance in a solid phase (Hewitt, 2010, p. 313)?