QUESTION TWO (a) Consider the process of heating water on top of an electric range. i. What are the forms of energy involved during this process? ii. What are the energy transformations that take place?
QUESTION TWO
(a) Consider the process of heating water on top of an electric range.
i. What are the forms of energy involved during this process?
ii. What are the energy transformations that take place?
(b) A classroom that normally contains 40 people is to be air-conditioned with window air-conditioning units of 5-kW cooling capacity. A person at rest may be assumed to dissipate heat at a rate of about 360 kJ/h. There are 10 light bulbs in the room, each with a rating of 100 W. The rate of heat transfer to the classroom through the walls and the windows is estimated to be 15,000 kJ/h. If the room air is to be maintained at a constant temperature of 21°C, determine the number of window air-conditioning units
required.
(c) Consider two closed systems A and B. System A contains 3000 kJ of thermal energy at 20°C, whereas system B contains 200 kJ of thermal energy at 50°C. Now the systems are brought into contact with each other. Determine the direction of any heat transfer between the two systems.
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