Two walls are made of the same type of concrete and have the same temperature difference between inside and outside. Wall A has twice the surface area as wall B but wall B is two times as thick as wall A. How does the heat loss through them compare? A) В. Wall A loses four times the heat as wall B) Wall A loses twice the heat as wall B. C) Wall A loses half the heat as wall B. Wall A loses a quarter of the heat as wall D) В.

Two walls are made of the same type of concrete and have the same temperature difference between inside and outside. Wall A has twice the surface area as wall B but wall B is two times as thick as wall A. How does the heat loss through them compare? A) В. Wall A loses four times the heat as wall B) Wall A loses twice the heat as wall B. C) Wall A loses half the heat as wall B. Wall A loses a quarter of the heat as wall D) В.

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter1: Temperature And Heat

Section: Chapter Questions

Problem 95P: (a) What is the rate of heat conduction through the 3.00-cm-thick fur of a large animal having a I...

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(a) What is the rate of heat conduction through the 3.00-cm-thick fur of a large animal having a I .40-m surface area? Assume that the animal's skin temperature is 32.0 , that the air temperature is 5.00 , and that has the same thermal conductivity as air. (b) What food intake will the animal need in one day to replace this heat transfer?
For the human body, what is the rate of heat transfer by conduction through the body's tissue with the following conditions: the tissue thickness is 3.00 cm, the difference in temperature is 2.00 , and the skin area is 1.50 m2. How does this compare with the average heat transfer rate to the body resulting from an energy intake of about 2400 kcal per day? (No exercise is included.)
Compare the rate of heat conduction through a 13.0-cm-thick wall that has an area of 10.0 m2 and a thermal conductivity that of glass wool with the rate of heat conduction through a 0.750-cm-thick window that has an area of 2.00 m2, assuming the same temperature difference across each.
(a) The number of kilocalories in food is determined by calorimetry techniques in which the food is burned and the amount of heat transfer is measured. How many kilocalories per gram ale there in a 5.00-g peanut if the energy from burning it is transferred to 0. 500 kg of water held in a 0.100-kg aluminum cup, causing a 54.9- temperature increase? Assume the process takes place in an ideal calorimeter, in other words a perfectly insulated container. (b) Compare your answer to the following labeling information found on a package of dry roasted peanuts: a sewing of 33 g contains 200 calories. Comment on whether the values are consistent.
In a study of healthy young men[1], doing 20 push-ups in 1 minute burned an amount of energy per kg that for a 70.0-kg man corresponds to 8.06 calories (kcal). How much would a 70.0-kg man's temperature rise if he did not lose any heat during that time?
A Carnot refrigerator exhausts heat to the air, which is at a temperature of 25 . How much is used by the refrigerator if it freezes 1.5 g of water per second? Assume the water is at 0 .
One method of converting heat transfer to doing work is for heat transfer into a gas to take place, which expands, dong work on a piston, as shown in the figure below. (a) Is the heat transfer converted directly to work in an isobaric process, or does it go through another form first? Explain your answer. (b) What about in an isothermal process? (c) What about in an adiabatic process (where heat transfer occurred prior to the adiabatic process)?
Most automobiles have a coolant reservoir to catch radiator fluid than may overflow when 1he engine is hot. A radiator is made of copper and is filled to its 16.0L capacity when at 10.0C. What volume of radiator fluid will overflow when the radiator and fluid reach their 95.0C operating temperature, given that the fluid’s volume coefficient of expansion is =400106/C ? Note that this coefficient is approximate, because most car radiators have operating temperatures of greater than 95.0C.
In 1986, a gargantuan iceberg broke away from the Ross Ice Shelf in Antarctica. It was approximately a rectangle 160 km long, 40.0 km wide, and 250 m thick. (a) What is the mass of this iceberg, given that the density of ice is 917kg/m3 ? (b) How much heat transfer (in joules) is needed to melt it? (c) How many years would it take sunlight alone to melt ice this thick, if the ice absorbs an average of 100W/m2, 12.00 h per day?
A firewalker runs across a bed of hot coals without sustaining burns. Calculate the heat transferred by conduction into the sole of one foot of a firewalker given that the bottom of the foot is a 3.00-mm-thick callus with a conductivity at the low end of the range for wood and its density is 300 kg/m3. The area of contact is 25.0 cm2 the temperature of the coals is 700 , and the time in contact is 1.00 s. Ignore the evaporative cooling of sweat.
Your house will be empty for a while in cold weather and want to save energy and money. Should you tum the thermostat down to the lowest level that will protect the house from damage such as freezing pipes, or leave it at the normal temperature? (If you don't like coming back to a cold house, imagine that a timer controls the heating system so the house will be warm when you get back.) Explain your answer.
(a) How much heat transfer is necessary to raise the temperature of a 0.200-kg piece of ice from -20.0 to 130.0 , including the energy needed for phase changes? (b) How much time is required for each stage, assuming a constant 20.0 kJ/s rate of heat transfer? (c) Make a graph of temperature versus time for this process.