A pan with initial temperature -25C is put in a room with temperature 25C. After half an hour, the skillet's temperature changes to -15C. 1. Find an expression for the pan's temperature as function of time.2. What is the pan's temperature after another half hour?3. When will the pan have warmed to 10C? to 25C? An object with initial temperature of -25°C is placed in a room kept at 25°C. After half anhour the object's temperature is – 15°C.2.(a) Find an expression for the object's temperature as function of time.(b) What is the object's temperature after another half hour?(c) When will the object have warmed to 10°C? When will the object have warmed to 25°C?|

Given: The initial temperature of the object, To = - 25 degree The room temperature, Ti = 25 degree…

An object with initial temperature of -25°C is placed in a room kept at 25°C. After half an hour the object's temperature is – 15°C. 2. (a) Find an expression for the object's temperature as function of time. (b) What is the object's temperature after another half hour? (c) When will the object have warmed to 10°C? When will the object have warmed to 25°C?|

An object with initial temperature of -25°C is placed in a room kept at 25°C. After half an hour the object's temperature is – 15°C. 2. (a) Find an expression for the object's temperature as function of time. (b) What is the object's temperature after another half hour? (c) When will the object have warmed to 10°C? When will the object have warmed to 25°C?|

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.26P

See similar textbooks

Similar questions

1.77 Explain each in your own words. (a) What is the mode of heat transfer through a large steel plate that has its surfaces at specified temperatures? (b) What are the modes when the temperature on one surface of the steel plate is not specified, but the surface is exposed to a fluid at a specified temperature?
1.63 Liquid oxygen (LOX) for the space shuttle is stored at 90 K prior to launch in a spherical container 4 m in diameter. To reduce the loss of oxygen, the sphere is insulated with superinsulation developed at the U.S. National Institute of Standards and Technology's Cryogenic Division; the superinsulation has an effective thermal conductivity of 0.00012 W/m K. If the outside temperature is on the average and the LOX has a heat of vaporization of 213 J/g, calculate the thickness of insulation required to keep the LOX evaporation rate below 200 g/h.
After the sinking of RMS Titanic, US operated the International Ice patrol with the purpose of monitoring the presence and movements of icebergs in the Atlantic and Arctic oceans. Once, they observed a unique tabular iceberg in a form of a rectangle (250 km x 50 km x 300 m). How many years would it take to melt the iceberg solely by heat from the sun if the ice absorbs a mean of 98 J/m2 -s, 12.5 hrs per day? Note: the exposed area for heating is 250 km x 50 km and the density is 920 kg/m3 . This is my solution.
c) What is the temperature of the iron heating element at x=30mm (in ∘C)? Use the origin defined in the given diagram. d) At which position x (in mm) does the iron heating element experience its highest temperature? e) In this scenario outlined in this question (constant heat generation under steady-state, 1-D conditions), can the temperature distribution in the iron ever be linear? Yes or No? Justify your reasoning.
The specific heat of copper is 0.093 cal/(g.°C) and the specific heat of gold is 0.031 cal/(g.°C). If 9.5 cal is supplied to one gram of copper and one gram of gold, the RATIO of temperature increase of gold to that of copper is:
A metal spoon and a wooden spoon are left overnight in a room. Why do we feel colder when we touch the metal spoon than when we touch the wooden one? a. Since metals usually have a lower heat capacity than non-metals, the metal spoon loose more heat to the room and consequently has a lower temperature b. Metals release heat faster than non-metals because of their higher thermal conductivity c. This is merely psychological since we are conditioned to think of metals as “cold” d. Metals absorb heat faster than non-metals because of their higher thermal conductivity
A steel bar has a temperature reading of 70°K inside storage A. it was then transferred to storage B wherein the air temperature if 10°K. After 3 minutes the temperature reading of the steel bar is 25°K. what would be the temperature of the steel after another 3minutes?
Q#01: Define the following:a) Steady and Transient state of heat transfer by the help of an example.b) If the area, thickness and temperatures are same across the material. Justify whichmaterial will transfer more heat, either the material with high thermal conductivity valueor the material with low thermal conductivity value?c) If the area and temperatures are same across the material. Explain whether thermalconductivity will have any effect on thickness or not?
For a specified heat input and a given volume which material will have the smallest tempera- ture rise (Use data book if necessary) (a) steel (b) aluminium (c) water (d) copper. When a hot metal piece is left to cool in air the time rate of cooling of the outer layer will be (a) slower at start and faster near the end (b) faster at start and slower near the end (c) both rates will be the same (d) this will depend on the material. (viii) A thin black plate at temperature T receives radiation from a surface at Temperature T1 and radiates to a surface at T2. If all surfaces are black at steady state (a) (T1 – T) > (T – T2) (b) (T1 – T) < (T – T2) (c) (T1 – T) = (T – T2) (d) can be any one of a, b or c. (ix) The temperature profile (in) a slab initially at a constant temperature and then allowed to cool by convection for a short time will be as shown in Fig : (a) E1.2a (b) E1.2b (c) E1.2c (d) E1.2d. Ti
A square piece is initially at 10 degrees Celsius everywhere. Each side is 0.05 m long. Then the four sides are instantly heated up to 25 degrees Celsius, 50 degrees Celsius, 30 degrees Celsius, and 0 degrees Celsius. a. Find how long it takes for the temperature profile of this square to become steady if the material is copper. What is the final temperature at the center of the square? b. Find how long it takes for the temperature profile of this square to become steady if the material is air. What is the final temperature at the center of the square? c. Which material takes longer to reach steady state and why?
The following graph shows the thermal behavior of 2 kg of a material called Uniandesato undergoing a solid-liquid phase transition. In a container, thermally insulated from the outside, 20 kg of liquid water at a temperature of 80°C are placed. In addition to this, an unknown amount of Uniandesato in a 100% solid state at its melting temperature (10°C) is added. The specific heat of water is 4186 J/kg°C. a) If the system reaches an equilibrium temperature of 60°C, calculate the initial amount of Uniandesato added to the container. b) Calculate the change in entropy during this process and show that it is consistent with the Second Law of Thermodynamics. Hint: Extract the necessary information to solve this problem from the graph.
The icecaps of Greenland and Antarctica contain about 1.75% of the total water (by mass) on the earth’s surface; the oceans contain about 97.5%, and the other 0.75% is mainly groundwater. Suppose the icecaps, currently at an average temperature of about somehow slid into the ocean and melted. What would be the resulting temperature decrease of the ocean? Assume that the average temperature of ocean water is currently 5.0 ℃.