An exercise room has 6 weight-lifting machines that have no motors and 7 treadmills each equipped with a 2.5-hp (shaft output) motor. The motors operate at an average load factor of 0.7, at which their efficiency is 0.77. During peak evening hours, all 12 pieces of exercising equipment are used continuously, and there are also two people doing light exercises while waiting in line for one piece of the equipment. Assuming the average rate of heat dissipation from people in an exercise room is 600 W, determine the rate of heat gain of the exercise room from people and the equipment at peak load conditions.
Chapter 22 - The thermal properties of materials can be at least partly explained by the movement of electrons and phonons. - Heat capacity and specific heat represent the quantity of energy required to raise the temperature of a given amount of material by one degree, and they are influenced by temperature, crystal structure, and bonding. - The thermal expansion of many engineered materials can be made to be near zero by properly controlling the combination of different phases that show positive and negative thermal expansion coefficients. - Because of thermal expansion, stresses develop in a material when the temperature changes. Care in design, processing, or materials selection is required to prevent failure due to therma
