We often cut a watermelon in half and put it into the freezer to cool it quickly. But usually we forget to check on it and end up having a watermelon with a frozen layer on the top. To avoid this potential problem a person wants to set the timer such that it will go off when the temperature of the exposed surface of the watermelon drops to 3°C. Consider a 25-cm-diameter spherical watermelon that is cut into two equal parts and put into a freezer at 212°C. Initially, the entire watermelon is at a uniform temperature of 25°C, and the heat transfer coefficient on the surfaces is 22 W/m2·K. Assuming the watermelon to have the properties of water, determine how long it will take for the center of the exposed cut surfaces of the watermelon to drop to 3°C. Answer: 46.7 min

Q: How much heat energy must be added to a 6.8-cm-diameter copper sphere to raise its temperature from…

A: CONCEPT: Given, Diameter of copper sphere = 6.8 cm Radius of copper sphere, r = 3.4 cm We know,…

Q: An insulated cup of water (145g water) at room temp (20C), is warmed by a 25g sample of aluminum at…

A:

Q: A 2.44 m wide by 1.15 m high metal plate must be insulated to prevent contact burn injuries. If the…

A:

Q: The emissivity of tungsten is 0.35. A tungsten sphere with radius 1.61 cm is suspended within a…

A:

Q: A copper teakettle with a circular bottom 30.0 cm in diameter has a uniform thickness of 2.5 mm. It…

A: diameter of bottom= 30 cm thickness=2.5 mm Temperature of burner= 150 C

Q: An electric toaster works by radiative heat transfer. On each side of a four-slice toaster, there…

A: Let P be defined as the power the toaster consumes while operating. Therefore, using Stefan’s law,…

Q: (a) How much heat transfer is required to raise the temperature of a 0.750-kg aluminum pot…

A:

Q: The “steam” above a freshly made cup of instant coffee is really water vapor droplets condensing…

A: The heat will be, Q=McΔT Also, Q=mLv Thus we have, ΔT=mLvMc

Q: Consider the rate of heat conduction through a double-paned window that has a 1.4-m2 area and is…

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Q: You have a double-pane window that is 120.0 cm wide by 80.0 cm tall; the gap between the window…

A: Step 1: Data provided in the problem Area of the window pan A=120 cm×80 cm=1.20 m×0.80 m=0.96…

Q: Suppose a house's walls are 14.5 cm thick and and have an average thermal conductivity twice that of…

A:

Q: A rubber ball of radius 2.52 m and emissivity 0.940 is heated to 128°C. HINT (a) Convert the given…

A: a) The given temperature in kelvin is TK=T°C+273=128+273=401K

Q: The highest waterfall in the world is the Salto Angel in Venezuela. Its longest single falls has a…

A: Using the conservation of energy, the kinetic energy at the bottom equals the potential energy at…

Q: long with a negligible thickness, and assume that the chip radiates heat evenly from both the top…

A: W=1.5cmL=2.5 cmemissivity =0.6E=0.41w

Q: A cylindrical bar of length L and radius R (L>>R) whose side walls are thermally insulated supports…

A:

Q: A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.4 m x 1.7 m. On a certain day,…

A: See below

Q: 50.0 g ice cube, intially at 0° C, is dropped into a Styrofoam cup containing 350 g of water,…

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Q: The maximum amount of water an adult in temperate climates can perspire in one hour is typically 1.8…

A:

Q: Help.... Its wintertime and you are in need of portable electrical heater for your room and you are…

A:

Q: dermatologist often remove small precancerours skin lesions by freezing them quickly with liquid…

A: It is given that,

Q: One winter day, the climate control system of a large university classroom building malfunctions. As…

A: The heat transfer and temperature change is related as, Q=mc∆T Here, Q is the heat transfer, m is…

Q: 97. As we drill down into the rocks of Earth's crust, the temperature typically increases by 3.0°C…

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Q: Liquid water turns out to have a higher density at 4C degrees than at any other temperature. What…

A: Thermal expansion coefficient describe the relation between the size of an object and change in the…

Q: (a) The number of kilocalories in food is determined by calorimetry techniques in which the food is…

A: Given: The mass of peanut is mp=4.6 g. The mass of water is m=0.6 kg. The mass of aluminium is…

Q: A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.5 m × 1.9 m. On a certain day,…

A:

Q: Randy is nervous oboOut Physics 102 exam that he can't concentrate. To relax he, goes to Starbucks…

A: volume of coffee (V) = 470 ml Initial temperature of coffee = 80oC Final temperature of coffee = 40o…

Q: The "steam" above a freshly made cup of instant coffee is really water vapor droplets condensing…

A: Given problem is based on the concept of heat transfer. There are three ways through which heat…

Q: A 5.157 kg loose bag of soil falls from unknown height at a construction site. What is height in m…

A:

Q: You have just been to the shops and purchased a 3kg bag of ice (assume all at 0°C) to cool a 24 pack…

A: Given: Mass of ice = 2 kg Initial temperature of ice = 0 degrees No of beverage containers = 24…

Q: You are thinking ahead to spring when one of your friends is having an outdoor wedding. Your plan is…

A: Given: M = mass of lemonade = 5.6 x103 kg = 5600 gm S = specific heat capacity of water = 1.0…

Q: heat transfer rate

A: Given: Width of plate is W=2.37 m Height of plate is H=1.17 m Heat transfer rate is Q·=123 W Initial…

Q: At the bottom of an old mercury-in-glass thermometer is a 35-mm³ reservoir filled with mercury. When…

A: Initial volume  Radius of capillary tube Change in temperature

Q: The figure shows a copper disk of radius r and thickness 1, with a hole through its centre of radius…

A:

Q: a) Two materials, aluminum (intial length, 6 m) and ordinary glass (initial length, 5 m) are…

A: The coefficient of expansion of aluminum is αAl = 23*10-6 oC The coefficient of expansion of glass…

Q: A 76.0-kg person suffering from hypothermia comes indoors and shivers vigorously. How long does it…

A: The shivering creates the energy of 425 W.  Therefore, from the expression of the heat transfer and…

Q: One winter day, the climate control system of a large university classroom building malfunctions. As…

A: Given: The volume of cold air is 500 m3. Time duration is 1 min. The temperature change is 10…

Q: You have just been to the shops and purchased a 3kg bag of ice (assume all at 0°C) to cool a 24 pack…

A:

Q: If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to…

A: Solution: Given that T0 =  -40 °F = 233.15 K T = 86 °F = 303.15 K

Calorimetry

Measuring the heat transferred during chemical reactions or other physical processes is known as calorimetry. It comes under the branch of thermochemistry.