Some engineers have developed a device that provides lighting to rural areas with no access to grid electricity. The device is intended for indoor use. It is driven by gravity, and it works as follows: A bag of rock or sand is raised by human power to a higher location. As the bag descends very slowly, it powers a sprocket-wheel which also rotates slowly. A gear train mechanism converts this slow motion to high speed, which drives a DC generator. The electric output from the generator is used to power an LED bulb. Consider a gravity-driven LED bulb that provides 16 lumens of lighting. The device uses a 10-kg sandbag that is raised by human power to a 2-m height. For continuous lighting, the bag needs to be raised every 20 minutes. Using an efficacy of 150 lumens per watt for the LED bulb, determine ( a ) the velocity of the sandbag as it descends and ( b ) the overall efficiency of the device.
Some engineers have developed a device that provides lighting to rural areas with no access to grid electricity. The device is intended for indoor use. It is driven by gravity, and it works as follows: A bag of rock or sand is raised by human power to a higher location. As the bag descends very slowly, it powers a sprocket-wheel which also rotates slowly. A gear train mechanism converts this slow motion to high speed, which drives a DC generator. The electric output from the generator is used to power an LED bulb. Consider a gravity-driven LED bulb that provides 16 lumens of lighting. The device uses a 10-kg sandbag that is raised by human power to a 2-m height. For continuous lighting, the bag needs to be raised every 20 minutes. Using an efficacy of 150 lumens per watt for the LED bulb, determine ( a ) the velocity of the sandbag as it descends and ( b ) the overall efficiency of the device.
Some engineers have developed a device that provides lighting to rural areas with no access to grid electricity. The device is intended for indoor use. It is driven by gravity, and it works as follows: A bag of rock or sand is raised by human power to a higher location. As the bag descends very slowly, it powers a sprocket-wheel which also rotates slowly. A gear train mechanism converts this slow motion to high speed, which drives a DC generator. The electric output from the generator is used to power an LED bulb.
Consider a gravity-driven LED bulb that provides 16 lumens of lighting. The device uses a 10-kg sandbag that is raised by human power to a 2-m height. For continuous lighting, the bag needs to be raised every 20 minutes. Using an efficacy of 150 lumens per watt for the LED bulb, determine (a) the velocity of the sandbag as it descends and (b) the overall efficiency of the device.
Branch of science that deals with the stationary and moving bodies under the influence of forces.
3. What is the energy equivalent of 1 lb (0.453 kg) of mass? What is the mass
equivalent of the electric energy produced by a 1,000 MW nuclear power
plant for an entire year?
A solar pond power plant produced power output at 350 kW and thermal efficiency of 4%.Sketch the schematic diagram of the system and determine the rate of solar energy collected.
An electric motor drives a compressor by
use of V-belt. The pulley diameter of the
compressor shaft is 1.1 meter while the
pulley diameter of the motor shaft is 0.6
meter. The belt speed runs at 27 m/s. The
center distance between pulleys is 1.75 m.
The groove angle of the pulleys is 35º.
Determine the power generated in kW if the
tension at the tight side of the belt is 670.5
N. The coefficient of friction between the
belt and the pulley is 0.23.
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