Aim: -to explain how Einstein predicted the possibility of releasing enormous amounts of energy.
-explain how scientists use theories to make predictions.
1. In 1905, was Einstein a nuclear physicist? Explain your answer.
No, because in 1905 Einstein was not even thinking about atom bombs. In fact, at this time, physicists did not know that atoms have a nucleus.
2a. what is the famous equation he published in his special theory of relativity?
The famous equation that he published in his special theory of relativity is:
b. what does each symbol in the equation stand for?
3. The fission of uranium-235 produces nuclei of barium and krypton (and some spare neutrons).
a. how will the mass of the products compare with the mass of the uranium nucleus?
The mass of the products will be less than the mass of the uranium nucleus.
b.what prediction did Lise Meitner make about the amount of energy that would be released?
By using Einstein’s equation (E=mcï¿½), she calculated that the fission reaction would release a million times more energy than a chemical reaction.
4. give an example, other than the special theory of relativity, of theories that can make predictions.
Another very successful and strong theory is Newton’s laws of motion which still continues to predict the paths of satellites and space rockets successfully.
5. Describe how Einstein’s theory eventually led to the exploding of the atom bomb. Make sure you include the predictions that were made from the theory and how they were tested.
* Two German scientists Otto Hahn and Lise Meitner bombarded uranium-235 with neutrons which produced barium. This meant that the uranium-235 nucleus had split in two- this process was called nuclear fission.
* Using Einstein’s equation (e=mc^2) Meitner calculated that the fission reaction would release a million times more energy than a chemical reaction.
* To conclude Meitner’s insight led to new experiments as it showed that it was possible to create a fission reaction with uranium-235. There were lots of atom bomb test sites, which countries (e.g. Germany-Hitler) tried to use fission to produce a weapon- so the race was on to create the atom bomb, which was created in 1945, and atomic bombs were detonated on the Japanese cities of Hiroshima and Nagasaki.
6. How are new theories accepted?
Aim: to explain that new scientific theories have to be validated by other scientists before they are accepted
1. Give some advantages of cold fusion over:
a. hot fusion
* Hot fusion requires pressurised containers which heat hydrogen to 50 million, but cold fusion can do it at 50 ï¿½C which is much closer to room temperature.
* Requires uranium-235, but fusion only needs the fuel hydrogen which is :
* Safe to use
* Readily available
* Produces practically no radioactive waste
* Fusion produces no carbon dioxide even though it can produce an enormous amount of energy.
2. why was the reaction known as cold fusion?
The reaction was known as ‘cold fusion’ because hot fusion requires 50 million ï¿½C to react hydrogen, but ‘cold’ fusion only requires 50ï¿½C, which is a lot closer to room temperature.
3. why was their announcement so exciting?
* Their announcement was so exciting because scientists had been trying for 30 years to produce energy from fusion.
* Most importantly, their announcement (the reports) raised hopes of a cheap and abundant source of energy.
4a. how did Fleischmann and Pons announce their results?
Fleischmann and Pons announced their results by holding a press conference.
4b. what is the more respected way of publishing results?
A more respected way of publishing results is if the papers describing the results are published in a respected and reputable publication e.g. a scientific journal.
5. explain what it meant by the term peer-review.
Peer reviewing is when the article is checked by other scientists before being published in a scientific journal.
6a. what does reproducible mean?
Reproducible means that other researchers can do the same experiment and get the same results.
6b. why is it important that scientific experiments are reproducible?
It is important that scientific experiments are reproducible, as this validates the scientific claim and ensures that the results are not just fake or good luck.
7. Is a press conference a good way to announce the results of a scientific discovery? Explain your answer.
* A press conference is not a good way to announce the results of a scientific discovery.
* A scientific discovery carries more weight if it is published as an article in a respected scientific journal/publication.