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Thepotemich [5.8K]
3 years ago
13

Some engineers have developed a device that provides lighting to rural areas with no access to grid electricity. The device is i

ntended 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.

Engineering
1 answer:
Vitek1552 [10]3 years ago
8 0

Complete Question

The complete question is shown on the first uploaded image

Answer:

The velocity of the sandbag as it descends is 1.875 mm/s

The overall efficiency of the device is 0.0484%

Explanation:

The explanation is shown on the second uploaded image

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Joe is a chemical engineer whose plant discharges heavy metals into the local river. By the test authorized by the city governme
chubhunter [2.5K]

Answer:

B probably

Explanation:

Because the prompt doesn't specify what sort of violation it could be anything maybe when they release the metals during the day and so on.

5 0
2 years ago
When _____ ,the lithium ions are removed from the_____ and added into the _____
bezimeni [28]

Answer:

b. Discharging; anode; cathode

Explanation:

When discharging , it means the battery is producing a flow electric current, the lithium ions are released from the  anode to the cathode which generates the flow of electrons from one side to another. When charging Lithium ions are released by the cathode and received by the anode.

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3 years ago
In order to defend against side channel power analysis, we should: ______________
wariber [46]

Answer:

Some examples of predator and prey are lion and zebra, bear and fish, and fox and rabbit. ... The words "predator" and "prey" are almost always used to mean only animals that eat animals, but the same concept also applies to plants: Bear and berry, rabbit and lettuce, grasshopper and leaf

Explanation:

8 0
2 years ago
Steam at 500 bar and 500°C undergoes a throttling expansion to 1 bar. What will be the temperature of the steam after the expans
aleksandr82 [10.1K]

T1=T2=500°C

<u>Explanation:</u>

Given-

Pressure, P1 = 500 bar

Temperature, T1 = 500°C

P2 = 1 bar

T2 after expansion, = ?

We know,

P1/T1 = P2/T2

500/ 500 = 1/T2

T2 = 1°C

If the steam were replaced by an ideal gas, since enthalpy of ideal gas is a function of temperature only, we easily obtain T2 = T1 = 500°C

8 0
3 years ago
Lets assume, a represents the edge length (lattice constant) of a BCC unit cell and R represents the radius of the atom in the u
uranmaximum [27]

Answer:

4\ R=\sqrt 3\ a

Explanation:

Given that

Lattice constant = a

Radius of unit cell cell =R

Atom is in BCC structure.

In BCC unit cell (Body centered cube)

1.Eight atoms at eight corner of cube which have 1/8 part in each cube.

2.One complete atom at the body center of the cube

So the total number of atoms in the BCC

 Z= 1/8 x 8 + 1 x 1

Z=2

In triangle ABD

AB^2=AD^2+BD^2

AB^2=a^2+a^2

AB=\sqrt 2\ a

In triangle ABC

AC^2=AB^2+BC^2

AC=4R

BC=a

AB=\sqrt 2\ a

So

16R^2=2a^2+a^2

4\ R=\sqrt 3\ a

So the relationship between lattice constant and radius of unit cell

4\ R=\sqrt 3\ a

7 0
3 years ago
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