# HELP PHYSICS alpha scattering

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Thread starter 3 years ago
#1
http://pmt.physicsandmathstutor.com/...s%201%20QP.pdf

Can someone help me with question 2biv? the markscheme just says 'correct explanation' - would like to know what this correct explanation is thank you

MS:http://pmt.physicsandmathstutor.com/...s%201%20MS.pdf
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3 years ago
#2
If the alpha particle travels 'much closer' to the nucleus such as to be affected by the strong nuclear force, it'll be attracted into the nucleus and fusion will occur, or at least the alpha particle will be captured by the nucleus, provided it has enough energy for this to occur. That's the only explanation I can muster for the strong force being involved. You'd need to overcome a lot of electrostatic repulsion for this, though.

Yall need at least a distance of 3-4 fm for it to get the strong force going for that, though.
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3 years ago
#3
(Original post by MrToodles4)
http://pmt.physicsandmathstutor.com/...s%201%20QP.pdf

Can someone help me with question 2biv? the markscheme just says 'correct explanation' - would like to know what this correct explanation is thank you

MS:http://pmt.physicsandmathstutor.com/...s%201%20MS.pdf
Range of strong nuclear force is 3-4fm.

I would assume that if the alpha particle travels closer than the value calculated in iii, then strong force acts on the alpha particle.

I think they want u to say that the magnitude of the resultant force decreases, then u could say that the resultant force becomes attractive or stays repulsive i think u will get the marks either way.

This is likely because the strength of the strong nuclear force is probz not on ur spec so they wouldnt expect u to know exactly what is going to happen, but they would expect u to have an idea of what would happen and both of the ideas i mentioned above seem plausible to me.
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Thread starter 3 years ago
#4
(Original post by Callicious)
If the alpha particle travels 'much closer' to the nucleus such as to be affected by the strong nuclear force, it'll be attracted into the nucleus and fusion will occur, or at least the alpha particle will be captured by the nucleus, provided it has enough energy for this to occur. That's the only explanation I can muster for the strong force being involved. You'd need to overcome a lot of electrostatic repulsion for this, though.

Yall need at least a distance of 3-4 fm for it to get the strong force going for that, though.
Yeah that makes sense but what would you say about the resultant force then? As the question asks how the strong nuclear force affects the resultant force...
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3 years ago
#5
(Original post by MrToodles4)
Yeah that makes sense but what would you say about the resultant force then? As the question asks how the strong nuclear force affects the resultant force...
Resultant will increase to attractive if it gets close enough, repulsive past 3-4 fm due to electrostatic, attractive 0.5-3/4 fm due to strong, and repulsive at >0.5fm due to strong and electrostatic repulsive.
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Thread starter 3 years ago
#6
(Original post by Shaanv)
Range of strong nuclear force is 3-4fm.

I would assume that if the alpha particle travels closer than the value calculated in iii, then strong force acts on the alpha particle.

I think they want u to say that the magnitude of the resultant force decreases, then u could say that the resultant force becomes attractive or stays repulsive i think u will get the marks either way.

This is likely because the strength of the strong nuclear force is probz not on ur spec so they wouldnt expect u to know exactly what is going to happen, but they would expect u to have an idea of what would happen and both of the ideas i mentioned above seem plausible to me.
It makes sense up to resultant force becomes attractive or stats repulsive - how can it be both?
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3 years ago
#7
(Original post by MrToodles4)
It makes sense up to resultant force becomes attractive or stats repulsive - how can it be both?
Well u dont know whats stronger, is the electrostatic repulsion stronger than the strong nuclear or vice versa. If repulsion is stronger the resultant will still be repulsive and vice versa.

If it were two protons or two helium nuclei then i would probably say the resultant force is attractive to allow fusion but the magnitude of the product of the charges of aluminium and and alpha particle is higher than between two protons, so the electrostatic repulsion would be greater.

So we know that the strong nuclear force will act on alpha particle but u don’t know if it is great enough to cause a net attractive force, so i think u could say any and as long as u don’t contradict urself.
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3 years ago
#8
(Original post by MrToodles4)
http://pmt.physicsandmathstutor.com/...s%201%20QP.pdf

Can someone help me with question 2biv? the markscheme just says 'correct explanation' - would like to know what this correct explanation is thank you

MS:http://pmt.physicsandmathstutor.com/...s%201%20MS.pdf
So there is obviously a repulsive electromagnetic force that is acting on the alpha particle as it approaches the nucleus as both the alpha particle and aluminium nucleus are positive charged. So excluding the strong nuclear force, there is going to only be one force acting on the left (ignoring any other trivial forces like weight which is negligible) which is that repulsive force and this would be the resultant force.

If we take the strong nuclear force into account, this is an attractive force between nucleons in the range of 0.5-3 fm. So in addition to the electrostatic repulsive force on the alpha particle on the left direction, there is also an attractive force on the right direction. So this means the overall resultant force acting leftwards will be smaller.
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Thread starter 3 years ago
#9
(Original post by Anonymouspsych)
So there is obviously a repulsive electromagnetic force that is acting on the alpha particle as it approaches the nucleus as both the alpha particle and aluminium nucleus are positive charged. So excluding the strong nuclear force, there is going to only be one force acting on the left (ignoring any other trivial forces like weight which is negligible) which is that repulsive force and this would be the resultant force.

If we take the strong nuclear force into account, this is an attractive force between nucleons in the range of 0.5-3 fm. So in addition to the electrostatic repulsive force on the alpha particle on the left direction, there is also an attractive force on the right direction. So this means the overall resultant force acting leftwards will be smaller.
Yeah I understand - the person above just said we don't know which force is stronger though
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Thread starter 3 years ago
#10
(Original post by Shaanv)
Well u dont know whats stronger, is the electrostatic repulsion stronger than the strong nuclear or vice versa. If repulsion is stronger the resultant will still be repulsive and vice versa.

If it were two protons or two helium nuclei then i would probably say the resultant force is attractive to allow fusion but the magnitude of the product of the charges of aluminium and and alpha particle is higher than between two protons, so the electrostatic repulsion would be greater.

So we know that the strong nuclear force will act on alpha particle but u don’t know if it is great enough to cause a net attractive force, so i think u could say any and as long as u don’t contradict urself.
I guess that makes sense. Thank you.

Could you also help me with 4b? here: http://pmt.physicsandmathstutor.com/...s%202%20QP.pdf

its quick Im just not sure what the markscheme is saying again.
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3 years ago
#11
(Original post by MrToodles4)
I guess that makes sense. Thank you.

Could you also help me with 4b? here: http://pmt.physicsandmathstutor.com/...s%202%20QP.pdf

its quick Im just not sure what the markscheme is saying again.
Are u familiar with the pattern of field lines between two similarly charged charges?

It just wants one line from each point that u would expect to see in that pattern.

Could u attach mark-scheme so i can see what it says
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Thread starter 3 years ago
#12
(Original post by Shaanv)
Are u familiar with the pattern of field lines between two similarly charged charges?

It just wants one line from each point that u would expect to see in that pattern.

Could u attach mark-scheme so i can see what it says

Yes I am familiar.
MS: http://pmt.physicsandmathstutor.com/...s%202%20MS.pdf
0
3 years ago
#13
Can u post a pic of what uve done?

I would assume its the same as the field lines u get when u push two similar poles of magnets together.

But u only want one line from A and one from B
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