Lava at Ty= 1050° C emerges from a volcano. A mass m = 65 kg of this lava flows at a constant velocity of v = 0.35 m/s losing Q = 12250 J of heat every second to the surroundings. The lava flows a distance of 250 m before reaching the ocean. Assume that the temperature of the surroundings, Turr = 23° C is unaffected by the cooling of the lava. Part (a) Calculate how long t in seconds it takes before this mass of lava reaches the ocean. Part (b) Calculate the amount of heat Q; in joules lost to the surroundings before this mass reaches the ocean. Part (c) If the specific heat capacity of the lava in this process is c = 840 J/ kg °C, calculate the temperature of this mass of lava T in celsius just before it reaches the ocean. Part (d) Calculate entropy change of the surroundings 4Sgurr in J/ K while the lava was moving toward the ocean. Part (e) Calculate the change in the entropy of the lava AS in joules per kelvin while the lava was moving toward the ocean.

The concrete slab of a basement is 11 m long and 8 m wide, and 0.20 m thick. During the winter, temperatures are nominally 17°C and 10°C at the top and bottom surfaces, respectively. If the concrete has a thermal conductivity of 1.4 W/mK, what is the rate of heat loss through the slab? If the basement is heated by a gas furnace operation at an efficiency of 90%, and natural gas is priced at $0.02. MJ, what is the daily cost of the heat loss. Answer: QLOSS = 4.312 kW, COST = $8.28/day

A pot on the stove contains 500 g of water at 20°C. An unknown mass of ice that is originally at −10°C is placed in an identical pot on the stove. Heat is then added to the two samples of water at precisely the same constant rate. Assume that this heat is transferred immediately to the ice or water (in other words, neglect the increase in temperature for the pot). We will also neglect evaporation. The ice melts and becomes water, and you observe that both samples of water reach 60.0°C at the same time. Solve for the mass of the ice that was originally in the second pot. The specific heat of liquid water is 4186 J/(kg °C), and of solid water is 2060 J/(kg °C). The latent heat of fusion of water is 3.35  105 J/kg.

19. The following fission reaction (shown below) occurs in a nuclear power plant. There are 1.50 x 1016 uranium-235 atoms that are simultaneously undergoing this reaction. The uranium is surrounded by 17.5 kg of heavy water, which has a specific heat capacity of 4.70 x 10³ J/kg °C. If 90% of the energy released in the nuclear reactions is absorbed as thermal energy by the heavy water, determine the increase in temperature of he heavy water. ✔✔✔✔ 235U+n→ Zr + 139 Te + 3(n) 92 40 52 mzr-94 = 93.906 u MTe-139 = 138.935 u Mu-235 = 235.044 u

Thermography is a technique for measuring radiant heat and detecting variations in surface temperatures that may be medically, environmentally, or militarily meaningful.(a) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 33.0C, such as on a person’s skin? (b) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 20.0C, such as for warm and cool automobile hoods?

Radioactive decay of elements in the earth’s interior results in a mean heat flux through the Earth’s surfaceof 5×10−2Wm−2. What is the flux expressed as a fraction of the energy flux due to thermal re-radiation of absorbed solar energy? If radioactive decay were the only heat source for the Earth, what would the Earth’s temperature be?

A small electric immersion heater is used to heat 79 g of water for a cup of instant coffee. The heater is labeled “72 watts" (it converts electrical energy to thermal energy at this rate). Calculate the time required to bring all this water from 20°C to 100°C, ignoring any heat losses. (The specific heat of water is 4186 J/kg-K.) Number Units