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sattari [20]
2 years ago
6

When Lisa placed a balloon to her ear, she was able to hear what her sister was whispering from the other side of the room. When

she removed the balloon, she was no longer able to hear what her sister was saying. What is the best explanation for what Lisa discovered?
Physics
2 answers:
Aleks04 [339]2 years ago
5 0

Explanation :

Helium gas is present inside air balloon. Its density is less than air i.e. it is lighter than air.

The speed of sound in air is 343 m/s and around 972 m/s in He.

So, when Lisa placed a balloon to her ear, she was able to hear what her sister was whispering from the other side of the room because the sound waves are travelling with faster speed to Lisa.

When she removed the balloon, she was no longer able to hear what her sister was saying. It is because speed of sound in air is <em>343 m/s</em>.

kipiarov [429]2 years ago
4 0

Answer:

The answer is D

Explanation:

Sound does not travel around the air outside of the balloon as well as it does through the denser air pressure inside the balloon

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2 years ago
A car travels 60 km in the first 2 hours and 68 km in the next 2 hours. What’s the cars average speed?
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Answer:

<u>The car's average speed is 32 kilometers per hour</u>

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Write a three-paragraph report on what you have learned. Be sure to include the uses of nuclear power, how it is generated, and
levacccp [35]
Advantages of Nuclear Energy1. Relatively Low Costs

The initial construction costs of nuclear power plants are large. On top of this, when the power plants first have been built, we are left with the costs to enrich and process the nuclear fuel (e.g. uranium), control and get rid of nuclear waste, as well as the maintenance of the plant.  The reason this is under advantages is that nuclear energy is cost-competitive. Generating electricity in nuclear reactors is cheaper than electricity generating from oil, gas and coal, not to speak of the renewable energy sources!

 

2. Base Load Energy

Nuclear power plants provide a stable base load of energy. This can work synergistic with renewable energy sources such as wind and solar. The electricity production from the plants can be lowered when good wind and solar resources are available and cranked up when the demand is high.

 

3. Low Pollution

It is in most cases more beneficial, in terms of the climate crisis, to replace other energy harnessing methods we use today with nuclear power. The environmental effects of nuclear power are relatively light compared to those. However, nuclear waste is potential harmful for both humans and the environment.

 

4. Thorium

Reports show that with the yearly fuel consumption of today’s nuclear power plants, we have enough uranium for 80 years. It is possible to fuel nuclear power plants with other fuel types than uranium. Thorium, which also is a greener alternative, has lately been given an increased amount of attention. China, Russia and India have already plans to start using thorium to fuel their reactors in the near future.

It looks like nuclear fuel is of good availability if we combine the reserves of the different types together. In other words, hopefully enough time for us to find cost-competitive greener ways of harnessing energy.

 

5. Sustainable?

Is nuclear energy renewable or non-renewable? This is a good question. By definition, nuclear energy is not a renewable energy source. As I mentioned above, there is a limited amount of fuel for nuclear power available. On the other hand, you could argue that nuclear energy is potentially sustainable by the use of breeder reactors and fusion reactors. Nuclear fusion is the holy grail of harnessing energy. If we can learn to control atomic fusion, the same reactions as those that fuel the sun, we have practically unlimited energy. At the moment, these two methods both have serious challenges that need to be dealt with if we are to start using them on larger scale.

 

6. High Energy Density

It is estimated the amount of energy released in a nuclear fission reaction is ten million times greater than the amount released in burning a fossil fuel atom (e.g. oil and gas). Therefore, the amount of fuel required in a nuclear power plant is much smaller compared to those of other types of power plants.

 

Disadvantages of Nuclear Energy

While the advantages of using nuclear energy seem to be many, there are also plenty of negative effects of nuclear energy. The following are the most important ones:

 

1. Accidents Happen

The radioactive waste can possess a threat to the environment and is dangerous for humans. We all remember the Chernobyl accident, where the harmful effects of nuclear radiation on humans can even be witnessed today. Estimates conclude that somewhere between 15 000 and 30 000 people lost their lifes in the Chernobyl aftermath and more than 2.5 million Ukrainians are still struggling with health problems related to nuclear waste.

Just last year, on March 18, a major nuclear crisis happenend again in Japan. While the casualties were not as high as with the Chernobyl accident, the environmental effects were disasterous.

History shows that we can never really protect us 100% against these disasters. Accidents do happen.

 

2. Radioactive Waste

Does nuclear power cause air pollution? The nuclear power plants emit negligible amounts, if any, carbon dioxide into the atmosphere.  However, the processes in the nuclear fuel chain such as mining, enrichment and waste management does.

 

There are many arguments both for and against nuclear power. All in all I would say that the future of nuclear power looks promising. With new generations of reactors, potential major breakthroughs such as nuclear fusion, the methods we use to harness nuclear energy will get better in the next coming years. The question is: Do we need nuclear power or are the renewables a better choice?

3 0
2 years ago
Read 2 more answers
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