Eva is in a closed, dark room. she uses her arm muscles to turn on a lamp. when she moves her hand closer to the lamp, the light heats her hand. the light bounces off the pages of a book and into her eyes. if this room is a closed system, what happens to the total amount of energy in the room? a. it increases, then decreases. b. it increases. c. it decreases. d. it remains constant.

A75-hp (shaft output) motor that has an efficiency of 91.0 percent is worn out and is to be replaced by a high-efficiency motor that has an efficiency of 95.4 percent. the motor operates 4368 hours a year at a load factor of 0.75. taking the cost of electricity to be $0.12/kwh, determine the amount of energy and money saved as a result of installing the high-efficiency motor instead of the standard motor. also, determine the simple payback period if the pu