Questão 9
UNICAMP 2020
(UNICAMP - 2020 - 1ª fase)
Nuclear fusion is a reaction in which atomic nuclei merge to form the nucleus of a new atom. The mass of the new atom’s nucleus is lower than the sum of the merging nuclei’s masses, a difference that is released as energy. This is, for instance, the reaction that occurs in the Sun. The energy released during fusion can be calculated by the equation , where
is the difference between the initial and final masses in the reaction, and
is the speed of light. When calculating the aforementioned energy, nucleus mass can be conveniently quantified using the atomic mass unit (u), which is roughly equivalent to 900 MeV (1 u
900 MeV). Consider the hypothetical nuclear fusion reaction
. Note that the masses of
,
and
are 222u, 4u, and 221u, respectively.
The amount of energy released in this reaction is
5 MeV.
450 MeV.
900 MeV.
4500 MeV.
Gabarito:
4500 MeV.
Resolução:
Soma das massas antes: 222 u + 4 u = 226 u
Massas após fusão: 221 u
Diferença de massa: 5 u
Se cada unidade de massa atômica (u) equivale a 900 MeV, 5 unidades de massa atômica equivalem a 4500 MeV.
Alternativa D.