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Modern Physics
3 Apr 2008 11:45:41 IST
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easy qns rates assured
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A nucleus of mass number 220, initially at rest, emits an 
-particle . If the Q value of the reaction is 5.5 MeV, the energy of the emitted -particle will be
(a)4.8 MeV
(b)5.4 MeV
(c)6.0 MeV
(d)6.8 MeV
-particle . If the Q value of the reaction is 5.5 MeV, the energy of the emitted -particle will be (a)4.8 MeV
(b)5.4 MeV
(c)6.0 MeV
(d)6.8 MeV
Ans b
okease tell me how to solve this what is Q value in this
rates assured
Comments (2)
8 Apr 2008 00:38:47 IST
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3 people liked this
to solve this Q , 1st what is Q value ?
Allow me to qoute goiit study material :
Nuclear fission:-
(1) The phenomenon of breaking a heavy nucleus in to two light nuclei of almost equal masses along with the release of huge amount of energy is called nuclear fission.
(2) The heavy atoms like uranium (which low binding energy per nucleon) undergo fission reaction to produce two stable nucleii and generate mass defect which convers in to energy
e.g
Dumb Question:
in which form is the energy released.
ans: Energy is released in the form of kinetic energy of fission fragments
Now if that be the case,
In the reaction
X (220) -----> Y ( 216 ) + alpha ( 4 )
The energy is released in the form of KE of fission fragments.
( Plz note that I m only using the concept in case of radioactivity)
nucleus of mass number 220, initially at rest. So conservation of momentum gives
0 = 216 v1 + 4 v2
v1 = - 4v2 / 216 = -v2 / 54
now conservation of energy gives
( 1/2) m1 v12 + ( 1/2) m2 v22 = Q
216 v12 + 4 v2 2 = 5.5 mev
216( -v2 / 54 )2 + 4 v2 2 = 5.5 mev
4 v2 2 = 5.4 Mev
The mass no of alpha is 4. so we keep it as it is. Or we can keep m2 for it which will give same result.
Allow me to qoute goiit study material :
Nuclear fission:-
(1) The phenomenon of breaking a heavy nucleus in to two light nuclei of almost equal masses along with the release of huge amount of energy is called nuclear fission.
(2) The heavy atoms like uranium (which low binding energy per nucleon) undergo fission reaction to produce two stable nucleii and generate mass defect which convers in to energy
e.g
Dumb Question:
in which form is the energy released.
ans: Energy is released in the form of kinetic energy of fission fragments
Now if that be the case,
In the reaction
X (220) -----> Y ( 216 ) + alpha ( 4 )
The energy is released in the form of KE of fission fragments.
( Plz note that I m only using the concept in case of radioactivity)
nucleus of mass number 220, initially at rest. So conservation of momentum gives
0 = 216 v1 + 4 v2
v1 = - 4v2 / 216 = -v2 / 54
now conservation of energy gives
( 1/2) m1 v12 + ( 1/2) m2 v22 = Q
216 v12 + 4 v2 2 = 5.5 mev
216( -v2 / 54 )2 + 4 v2 2 = 5.5 mev
4 v2 2 = 5.4 Mev
The mass no of alpha is 4. so we keep it as it is. Or we can keep m2 for it which will give same result.
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nucleus of mass number 220, initially at rest. So conservation of momentum gives
0 = 216 v1 + 4 v2
v1 = - 4v2 / 216 = -v2 / 54
now conservation of energy gives
( 1/2) m1 v12 + ( 1/2) m2 v22 = Q
108 v12 + 2 v2 2 = 5.5 mev
108 ( -v2 / 54 )2 + 2 v2 2 = 5.5 mev
2 v2 2 = 5.4 Mev
** edited.