use the Kinetic Energy equation Ek = 0.5mv^2. look at the different masses
Original post by SALENTRAT
use the Kinetic Energy equation Ek = 0.5mv^2. look at the different masses
ya got it just realised that what I thought the answer was dumb!
Ok can I do this take ratio of 222 and 4 which is 111/2 so just multiply the E by 111/2?
Edit: can I just assume that they will move by same velocity though?
(edited 11 years ago)
Original post by AS01
A stationary nucleus of mass 226 u disintegrates into an alpha particle of mass 4 u and a residual nucleus of mass 222 u. If the kinetic energy of the alpha particle is E calculate the kinetic energy of the residual nucleus.
Is the answer E for residual nucleus as well?
Is the answer E for residual nucleus as well?
No, you need to consider momentum first.
The alpha and the residual nucleus will travel in opposite directions such that their momentum is the same, (but opposite in direction). This is because the initial momentum of the parent nucleus was zero, and the two product nuclei have equal and opposite momenta to give a total of zero.
Original post by Stonebridge
No, you need to consider momentum first.
The alpha and the residual nucleus will travel in opposite directions such that their momentum is the same, (but opposite in direction). This is because the initial momentum of the parent nucleus was zero, and the two product nuclei have equal and opposite momenta to give a total of zero.
The alpha and the residual nucleus will travel in opposite directions such that their momentum is the same, (but opposite in direction). This is because the initial momentum of the parent nucleus was zero, and the two product nuclei have equal and opposite momenta to give a total of zero.
That makes sense. But how will it give me energy of particle though? do I just see the KE?
I even tried looking for the some formula but energy and momentum have same SI unit.
Original post by AS01
ya got it just realised that what I thought the answer was dumb!
Ok can I do this take ratio of 222 and 4 which is 111/2 so just multiply the E by 111/2?
Edit: can I just assume that they will move by same velocity though?
Ok can I do this take ratio of 222 and 4 which is 111/2 so just multiply the E by 111/2?
Edit: can I just assume that they will move by same velocity though?
They don't have the same velocity.
You have correctly shown that the velocities are in the ratio 111/2 (or 55.5 to 1 for the alpha to the residual nucleus)
You also know that kinetic energy is ½mv²
So what would be the ratio of the energy of the alpha to that of the residual nucleus?
You know the ratio of their masses and the ratio of their velocities. It doesn't just depend on the ratio of the velocities.
Original post by Stonebridge
They don't have the same velocity.
You have correctly shown that the velocities are in the ratio 111/2 (or 55.5 to 1 for the alpha to the residual nucleus)
You also know that kinetic energy is ½mv²
So what would be the ratio of the energy of the alpha to that of the residual nucleus?
You know the ratio of their masses and the ratio of their velocities. It doesn't just depend on the ratio of the velocities.
You have correctly shown that the velocities are in the ratio 111/2 (or 55.5 to 1 for the alpha to the residual nucleus)
You also know that kinetic energy is ½mv²
So what would be the ratio of the energy of the alpha to that of the residual nucleus?
You know the ratio of their masses and the ratio of their velocities. It doesn't just depend on the ratio of the velocities.
bt those 222u and 4u are the masses so the ratio gonna be 55.5 for mass and for velocity its square of 55.5?
Original post by AS01
bt those 222u and 4u are the masses so the ratio gonna be 55.5 for mass and for velocity its square of 55.5?
Yes the ratio of the masses is 55.5 to 1 for the residual nucleus to the alpha.
The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)
Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.
Can you see what the answer is?
Original post by Stonebridge
Yes the ratio of the masses is 55.5 to 1 for the residual nucleus to the alpha.
The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)
Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.
Can you see what the answer is?
The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)
Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.
Can you see what the answer is?
I still did not get u. I asked my teacher and he said its not required for us u only do that at uni level so cant be bothered
Original post by Stonebridge
Yes the ratio of the masses is 55.5 to 1 for the residual nucleus to the alpha.
The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)
Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.
Can you see what the answer is?
The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)
Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.
Can you see what the answer is?
can u please help me on this qsn?
An atom of mass is initially at rest, in its ground state. A moving (nonrelativistic) electron of mass collides with the atom. The atom+electron system can exist in an excited state in which the electron is absorbed into the atom. The excited state has an extra, "internal," energy relative to the atom's ground state.
Find the kinetic energy that the electron must have in order to excite the atom.
Express your answer in terms of E, me, and M .
Original post by Stonebridge
Yes the ratio of the masses is 55.5 to 1 for the residual nucleus to the alpha.The ratio of the velocities is 1 to 55.5 (the other way round, in other words.)Finally we have the kinetic energy ratio of the alpha to the residual nucleus depends on the mass but the velocity squared.Can you see what the answer is?
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