Thermal Quiz2 complete

Bold , color font , or underline your answer 1) On a cold day, a piece of metal feels much colder to the touch than a piece of wood. This is due to the difference in which one of the following physical property? a) density b) specific heat c) latent heat d) thermal conductivity 2) During a hot shower, water vapor condenses into water droplets, on your skin and on other bathroom surfaces such as your bathroom mirror. This will cause the temperature of your skin and the bathroom mirror to a ) increase b) decrease c) stay constant d) freeze 3) The reason ocean temperatures do not vary drastically is that a) water has a relatively high rate of heat conduction. b) water is a good radiator. c) water has a relatively high specific heat. d) water is a poor heat conductor. 4) The latent heat of vaporization is 580 kcal/kg at 37°C and 539 kcal/kg at 100°C for water. How can this difference be accounted for at the molecular level? a) It can't. b) At 100°C, the average kinetic energy of the molecules is greater, so less additional energy is needed to break molecules free from the rest of the liquid. c) At 100°C, the average kinetic energy of the molecules is greater so more additional energy must be delivered to break molecules free from the rest of the liquid. d) At 37°C there will be fewer molecules in the vapor state resulting in a lower vapor pressure while at 100°C there will be more molecules already present as vapor. e) 580 minus 37 is equal to 539 5) Suppose the latent heat of vaporization of H 2 O were one-tenth its actual value. 1. Other things being equal, would it take the same time, a shorter time, or a longer time for a pot of water on a stove to boil away? 1. Same time 2. Shorter time 3. Longer time 2. Would the evaporative cooling mechanism of the human body be as effective? 1. Yes 2. No

6) Water has unique qualities regarding its 1. Heat capacities 2. Thermal conduction 3. Thermal expansion 4. Latent heat of fusion 5. Latent heat of vaporization Which property of water helps to stabilize your body temperature? 1 2 3 4 5 Which property of water cools you when you perspire? 1 2 3 4 5 You wouldn’t put your hand in boiling water (at 212  ) yet you can put your hand in a 212  oven. Which property of water explains this? 1 2 3 4 5 7) Security systems can be set up to determine the presence of an intruder by detecting the infrared radiation from the intruder. Suppose the good guys have to get into a room with this type of system. The movie solution, which should work if it did not set off the alarm before the good guy got in, was to adjust the heating/cooling controls for that room so: a). the room was much cooler than normal. b) the room was warmed to human body temperature . c) the room was warmed so it was much warmer than human body temperature. d) these ventilation systems were turned off and the person entering the room was completely dressed in black. e) the conduction from the convection loops totally blocked the thermal radiation resulting in an incomplete heat transfer. 8) Fanning yourself on a hot day (say, 100°F, or 38°C) cools you by (a) increasing conductivity (b) decreasing the mean free path of the air (c) increasing the radiation rate of the skin (d ) increasing the evaporation of perspiration (e) none of these. 9) A strong wind on a cold day can produce -80 wind chills. This number is NOT appropriate for estimating: a) how cold a car will get if parked outside overnight. b) how long it will take for an automobile engine to cool off after it stops. c) the rate at which heat will be lost from a heated space such as a car with the heater running. d) any of these. e) No, wind chill is a good measure for all of these. 10) Heat transfer within a mammal's body is primarily by: a) radiation. b) convection c) conduction d ) all off these in almost equal amounts e) none of these in any appreciable amount.