Fission/Fusion reactions confusion help

1. Nov 14, 2012

Fission/Fusion reactions confusion help plz

1. The problem statement, all variables and given/known data
http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s03_qp_4.pdf
number 6

http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s04_qp_4.pdf
8
2. Relevant equations
E=mc^2

3. The attempt at a solution
Can someone clarify 6a for me please? The answer says "greater binding energy gives rise to release of energy", which seems quite vague

Also for the second question, it says "energy released in this fission reaction", but if you were to write down the equation, the energy you get at the right hand side is a negative, which means energy is needed for the reaction to occur?

235(1.2191)=144(a.3341)+90(1.3864)+E
in the end i get, 0=30.4+E ?

2. Nov 14, 2012

Basic_Physics

Re: Fission/Fusion reactions confusion help plz

6a The mass difference between the parent and daughter nucleus is the released energy, 0.55 MeV, which suggests that the parent nucleus has the larger binding energy (more massive nuclei will require more energy to break them apart). This can also be seen from the fact that a neutron was changed into a proton by the decay and the rest mass of a proton is slightly smaller than that of a neutron.