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Alex
3 years ago
12

Which statements define factors that contribute to the decline of Roman Empire

Physics
1 answer:
USPshnik [31]3 years ago
7 0
The Huns' invasion of Europe caused a mass migration driving Germanic tribes of Northern Europe to the borders of the Roman Empire which led to the Barbarian attacks on Rome. 
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Which scenario presents a possible environmental impact due hydrogen fuel cells?
Mekhanik [1.2K]

The scenario that presents a possible environmental impact due to hydrogen fuel cells is that, the electricity used to supply the fuel cells with Hydrogen is produced using fossil fuels.

The question is incomplete, but these should have been the options;

a.) The fuel cells are used to power internal combustion engines rather than electric motors.

b.) The electricity used to supply the fuel cells with hydrogen is produced using fossil fuels.

c.) The combined exhaust emissions from fleets of buses equipped with fuel cells generates smog.

d.) None of these are correct.

The answer therefore is option B. The Hydrogen fuel cell is a device that uses Hydrogen as an energy source to power machines and to generate heat and electricity. It is a green energy alternative to fossil fuels as unlike fossil fuels, it doesn't produce green house gases and is non-toxic. Also, unlike other clean sources of energy like wind and water, it doesn't require a large area of land to be produced.

Hydrogen fuel cells work by combining hydrogen and oxygen atoms. The resulting energy produced is converted to electrical energy which can be used to power electrical motors, while the by-product, water is non-toxic, renewable and doesn't create smog.

However, to produce the hydrogen used in the cells, high amount of energy is required in order to separate hydrogen from oxygen. To accomplish this, fossil fuels such as coal, natural gas and oil are used, releasing harmful emissions which creates a negative environmental impact. This makes the answer to the above question option B. A better alternative though, is to use other renewable energy sources like wind or solar.    

To learn more about the benefits of Hydrogen fuel cells, visit;

brainly.com/question/6501095

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8 0
2 years ago
which view of the macroeconomy suggests that the speed of adjustment Purcell correction would be very quick
horsena [70]

Rational expectations theory suggests that the speed of adjustment Purcell correction would be very quick.

<h3>What Is Rational Expectations Theory?</h3>

The rational expectations theory is a widely used concept and modeling technique in macroeconomics. Individuals make decisions based on three primary factors, according to the theory: their human rationality, the information available to them, and their past experiences.

The rational expectations hypothesis was originally suggested by John (Jack) Muth 1 (1961) to explain how the outcome of a given economic phenomena depends to a certain degree on what agents expect to happen.

  • People who have rational expectations always learn from their mistakes.
  • Forecasts are unbiased, and people make decisions based on all available information and economic theories.
  • People understand how the economy works and how government policies affect macroeconomic variables like the price level, unemployment rate, and aggregate output.

To learn more about Rational expectations theory from the given link

brainly.com/question/16479910

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7 0
2 years ago
Which of the following includes an example of a chemical property of an element?
Romashka [77]

Answer: D

Explanation:

5 0
4 years ago
engineers are using computer models to study train collisions design safer train cars. They start by modeling an elastic collisi
Archy [21]

Answer:

The final velocity of the second car is 57 m/s south.

Explanation:

This is an elastic collision between two train cars. In this case, the total kinetic energy between the two bodies will remain the same.

The formula to apply is :

m_1v_1i +m_2v_2i=m_1v_1f+m_2v_2f

where ;

m_1=mass of object 1\\v_1i=initial  velocity object1\\m_2=mass of object2\\v_2i=initial velocity object 2\\v_1f=final velocity object 1\\v_2f=final velocity object 2

Given in the question that;

m_1=14650kg\\v_1i=18m/s\\m_2=3825kg\\v_2i=11m/s\\v_1f=6m/s\\v_2f=?

Apply the formula as;

m_1v_1i +m_2v_2i=m_1v_1f+m_2v_2f

{14650*18}+{3825*11} = {14650 *6} + {3825 * v₂f}

263700+42075=87900 + 3825v₂f

305775 =87900 + 3825v₂f

305775-87900 = 3825v₂f

217875=3825v₂f

217875/3825 =v₂f

56.96 = v₂f

<u>57 m/s = v₂f { nearest whole number}</u>

4 0
3 years ago
Read 2 more answers
An ideal refrigerator does 130. 0 j of work to remove 780. 0 j of heat from its cold compartment during each cycle. what is the
zheka24 [161]

The refrigerator's coefficient of performance is 6.

The heat extracted from the cold reservoir Q cold (i.e., inside a refrigerator) divided by the work W required to remove the heat is known as the coefficient of performance, or COP, of a refrigerator (i.e., the work done by the compressor). The required inside temperature and the outside temperature have a significant impact on the COP.

As the inside temperature of the refrigerator decreases, its coefficient of performance decreases. The coefficient of performance (COP) of refrigeration is always more than 1.

The heat produced in the cold compartment, H = 780.0 J

Work done in ideal refrigerator, W = 130.0 J

Refrigerator's coefficient of performance = H/W

                                                                     = 780/130

                                                                     = 6

Therefore, the refrigerator's coefficient of performance is 6.

Energy conservation requires the exhaust heat to be = 780 + 130

                                                                                          = 910 J

Learn more about  coefficient here:

brainly.com/question/18915846

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5 0
2 years ago
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