versity campus has 200 classrooms and 400 faculty offices. The classrooms are equipped with 12 fluorescent tubes, each uming 110 W, including the electricity used by the ballasts. The faculty offices, on average, have half as many tubes. The us is open 240 days a year. The classrooms and faculty offices are not occupied for an average of 4 h a day, but the lights are on. If the unit cost of electricity is $0.175/kWh, determine how much the campus will save a year if the lights in the classrooms aculty offices are turned off during unoccupied periods. lights in the classrooms and faculty offices are turned off during unoccupied periods, the campus will save $ per yr.

If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of

The surface of a 0.5-m diameter space probe dissipates 150 W of heat to the outside. If the probe surface emits 80% of the heat that comes from the electronic equipment inside of it and the probe does not receive radiation from other surfaces, compute for the surface emissive power in : m²°

The sun's intensity at the distance of the earth is 1370 W/m2W/m2. 30%% of this energy is reflected by water and clouds; 70%% is absorbed. What would be the earth's average temperature (in ∘C∘C) if the earth had no atmosphere? The emissivity of the surface is very close to 1. (The actual average temperature of the earth, about 15 ∘C∘C, is higher than your calculation because of the greenhouse effect.) Express your answer to two significant figures and include the appropriate units.

A large machine sitting on the floor in a workshop emits noise with the following power 1W/125HZ, 1.5W/250HZ, 2W/500HZ, 2.5W/1000Hz, and 2W/2000Hz. The dimension of the workshop is 20OmX15m with 6m ceiling. The walls, ceiling and floor have average absorption of 0.05, 0.6 and 0.02, respectively. If the machine is located at 5m from one end of the workshop, and an office wall needs to be built at 5m from the other end, calculate: The SWL in each frequency band, a) Room constants R for the workshop and office. b) The sound pressure level in front of the office wall location A in each frequency band, c) The loudness of the noise at location A in each frequency band and the total loudness, d) If the transmission loss of the office wall is 20DB, what is the maximum loudness inside the office, e) How many hours can a person stay inside the office without exceeding the daily noise dose (DND)? 25m 15m 5m 5m

When an isolated system undergoes a process during which its kinetic energy reduces by 10 J and its potential energy increases by 20 J. Its internal energy change in J is O unknown О-10 O +10 о -30 О +30

If the price of electricity is $0.11/kWh, determine the amount of energy and money that will be saved as a result of installing motion sensors. Also, determine the simple payback period if the purchase price of the sensor is $32 and it takes 1 h to install it at a cost of $40.

rド-1 rf-1 Lk(rc-1)] 1 1. Derive the formula of thermal efficiency e =

Based on the following information, how does a 1000W microwave compare to the stovetop and electric kettles in terms of water-heating efficiency? Calculate both electricity-to-heat and overall efficiency (assuming electricity from a natural gas fired power plant). Please express your answer as a percentage. ​ -A 1000W microwave takes 120 seconds to boil 8 oz of water. -The boiling point of water is 100°C, and room temperature water is 20°C -The specific heat of water is 4.186 J/gC

3. 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 210C, determine the number of window air-conditioning units required. draw a figure also, and explain each step by step solution.