A workshop measures 7m x 13m and is lighted by 10 lamps which are rated at 200 W and have an efficiency of 15 lumen per watt. Assuming a depreciation factor of 0.67 and a coefficient of utilization of 0.5, find the illumination on the working plane. a. 102.4 lux b. 112.3 lux c. 123.3 lux d. 110.4 lux

6. A 2 kg mass is dropped to the ground through a conducting loop. The mass starts 3 meters off the ground with zero velocity, and it lands with a velocity 7 meters/second. You may take g to be 9.8 m/s^2 and ignore all other forces than gravity and electricity + magnetism. How much energy did the conducting loop dissipate (release) as heat and how do you know?

11) Two identical metal plates are painted, one matt white and the other matt black. These are placed at equal distances from a radiant heater as shown in the diagram. The heater is turned on for five minutes 11 iko pe ara. erta ke matt white metal plate radiant matt black metal plate heater Which metal plate absorbs more energy and which plate emits more energy in this time? mengc an den im mas absorbs emits more more A black B black black C white D white white black white

92. ao If the price of electrical energy is $0.10 per kilowatt · hour, what is the cost of using electrical energy to heat the water in a swimming pool (12.0 m × 9.00 m × 1.5 m) from 15 to 27 °C?