An average sleeping person metabolizes at a rate of about 80 W by digesting food or burning fat. Typically, 20% of this energy goes into bodily functions, such as cell repair, pumping blood, and other uses of mechanical energy, while the rest goes to heat. Most people get rid of all this excess heat by transferring it (by conduction and the flow of blood) to the surface of the body, where it is radiated away. The normal internal temperature of the body (where the metabolism takes place) is 37C, and the skin is typically 7 C cooler. By how much does the person’s entropy change per second due to this heat transfer?

A 95.0-kg block of ice at 0.00°C breaks off from a glacier, slides along the frictionless ice to the ground from a height of 2.43 m, and then slides along a horizontal surface consisting of gravel and dirt. Find how much of the mass of the ice is melted by the friction with the rough surface, assuming 75.0% of the internal energy generated stays in the ice. Latent heat of fusion (Lf) for water 333,700 J/kg.

You read in a popular diet blog that the author claims you can lose up to half a pound of body fat per week if, instead of drinking 1.9 liters (i.e., 1.9 kilograms) of water every day, you can eat the same amount of water in the form of ice. The reasoning is that your body must first melt the ice and then bring the ice water up to the body temperature of 37°C, which is a process that requires a significant amount of energy at the expense of “burned” body fat. Thankfully, you just finished discussing heat and phase changes in your physics class, so you can calculate exactly how much energy is expended. The specific heat and latent heat of fusion for water are 4.186 × 103 J/(kg⋅°C) and 3.34×105 J/kg, respectively a)  How many kilocalories do you expend when you eat 1.9 kg of ice at 0°C? Note that 1 kcal = 4186 J.  b) Assuming the metabolism of one pound of body fat produces 3500 kcal of energy, how many pounds of body fat could you lose in a week just by eating 1.9 kilograms of ice every…

A block of copper with a mass of 1.75 kg, initially at a temperature of 150.0°C, is in a well-insulated container. Water at a temperature of 26.0°C is added to the container, and the entire interior of the container is allowed to come to thermal equilibrium, where it reaches a final temperature of 66.0°C. What mass of water (in kg) was added? Assume any water turned to steam subsequently recondenses.  ?kg

An insulated container is partly filled with oil. The lid of the container is removed, 0.150 kg of water heated to 84.0°C is poured in, and the lid is replaced. As the water and the oil reach equilibrium, the volume of the oil increases by 1.00x105 m³. The density of the oil is 919 kg/m³, its specific heat capacity is 1980 J/(kg-C°), and its coefficient of volume expansion is 726x10-6 (Cº)-¹. What is the temperature when the oil and the water reach equilibrium? Number Units

Equal masses of substance A at 98.1°C and substance B at 26.2°C are placed in a well-insulated container of negligible mass and allowed to come to equilibrium. If the equilibrium temperature is 77.4°C, which substance has the larger specific heat? a) substance A     b) The answer depends on the exact initial temperatures. c) More information is required. d) The specific heats are identical.

A certain substance has a mass per mole of 41 g/mol. When 315 J is added as heat to a 33.0 g sample, the sample's temperature rises from 27.0°C to 41.0°C. What are the (a) specific heat and (b) molar specific heat of this substance? (c) How many moles are present? (a) Number Units (b) Number Units (c) Number Units

A 0.100 kg piece of ice at initial temperature −5.00 ◦C is placed in a perfectly insulated container with 1.00 kg (1 L) of water at initial temperature 20.0 ◦C. The container absorbs or releases no heat. All of the ice melts as the system reaches an equilibrium temperature Tf .  How much heat must the ice exchange with the rest of the system to raise its temperature to the melting point, 0.00 ◦C? Would this heat exchanged be positive, zero, or negative? Once the ice reaches its melting point, how much heat must the ice exchange with the rest of the system to melt? Would this heat exchanged be positive, zero, or negative? Once the ice melts, it is liquid water at 0.00 ◦C. Write an expression for the heat exchanged by the newly-melted ice QI to reach the equilibrium temperature Tf . Would you expect QI to be positive, zero, or negative? Write an expression for the heat exchanged by the original water QW to reach the equilibrium temperature Tf from its initial temperature. Assuming no…

Water with a mass of mW = 0.400 kg and temperature of TW = 15.5°C is poured into an insulated bucket containing mI = 0.19 kg of ice at a temperature of TI = -15°C. Assume the specific heats of ice and water are constant at cI = 2.10×103 J/(kg⋅°C) and cW = 4.19×103 J/(kg⋅°C), respectively. The latent heat of fusion for water is Lf = 334×103 J/kg.  Part (a)  What is the final temperature of the mixture, in degrees Celsius?  Tfinal =         Part (b)  Enter an expression for the mass of ice, in kilograms, that has melted when the mixture reaches its final temperature.  mmelt =     Part (c)  Calculate how much ice, in kilograms, has melted when the mixture reaches its final temperature.  mmelt =

A typical nuclear reactor generates 1000 MW of electric energy. In doing so, it produces “waste heat” at a rate of 2000 MW, and this heat must be removed from the reactor. Many reactors are sited next to large bodies of water so that they can use the water for cooling. Consider a reactor where the intakewater is at 18°C. State regulations limit the temperature of the output water to 30°C so as not to harm aquatic organisms. How many kilograms of cooling water have to be pumped through the reactor each minute?