Mini Progress Check – Self, Peer or Teacher Assess
Name:
Score/Grade:
Fundamental Particles - Review Question 25 marks
I think/reply.....
1.
(i)
State the quark composition of the neutron.
........................................................................................................................
[1]
(ii)
Complete the table to show the charge Q, baryon number B and strangeness S for the quarks
in the neutron.
quark
Q
B
S
[2]
(iii)
Hence deduce the values of Q, B and S for the neutron.
Q ................... B ................... S ...................
[1]
[Total 4 marks]
2.
Tritium-3 ( 31 H ) decays to helium-3 ( 32 He ) with the emission of a – particle.
(i)
Name the force responsible for this decay process.
........................................................................................................................
[1]
(ii)
Write a nuclear equation to represent this process.
[1]
Mr Powell 2013
1
Mini Progress Check – Self, Peer or Teacher Assess
(iii)
Write a quark equation, in its simplest form, to represent this process.
[2]
[Total 4 marks]
3.
With particular reference to two kinds of hadron, discuss the stability or otherwise of hadrons.
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[Total 5 marks]
Mr Powell 2013
2
Mini Progress Check – Self, Peer or Teacher Assess
4.
(a)
The table of Fig. 1 shows four particles and three classes of particle.
hadron
baryon
lepton
neutron
proton
electron
neutrino
Fig. 1
Indicate using ticks, the class or classes to which each particle belongs.
[2]
(b)
The neutron can decay, producing particles which include a proton and an electron.
(i)
State the approximate half-life of this process.
...............................................................................................................
[1]
(ii)
Name the force which is responsible for it.
...............................................................................................................
[1]
(iii)
Write a quark equation for this reaction.
...............................................................................................................
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[2]
(iv)
Write number equations which show that charge and baryon number are conserved
in this quark reaction.
charge ..................................................................................................
...............................................................................................................
baryon number .....................................................................................
...............................................................................................................
[2]
Mr Powell 2013
3
Mini Progress Check – Self, Peer or Teacher Assess
(c)
Fig. 2 illustrates the paths of the neutron, proton and electron only in a decay process of the
kind described in (b).
proton
neutron
electron
Fig. 2
Fig. 3 represents the momenta of the neutron, pn, the proton, pp and the electron, pe on a
vector diagram.
pe
pp
pn
Fig. 3
(i)
Draw and label a line on Fig. 3 which represents the resultant pr of vectors pp and pe.
[1]
(ii)
According to the law of momentum, the total momentum of an isolated system
remains constant.
Explain in as much detail as you can, why the momentum pr is not the same as pn.
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[3]
[Total 12 marks]
Mr Powell 2013
4
Mini Progress Check – Self, Peer or Teacher Assess
Answers
1.
(i)
up down down / udd;
(ii)
Q
u (+)2/3
d –1/3
(iii)
so for neutron
1
B
(+)1/3
(+)1/3
S
0
0
u values (1)
d values (1)
2
Q=0
B=1
S=0
1
[4]
2.
(i)
weak (force / interaction); (1)
(ii)
3
(iii)
d → u + e + v ; (2)
1H
1
→ 32He + 0–1e + v ; (1)
1
d → u gets 1/2
u
d → u + e / β + v is not in simplest form, so gets ½
d
baryon reaction 10n → 11p + 0–1e + v gets ½
2
[4]
3.
all free hadrons (thought to be) (somewhat) unstable; (1)
protons and neutrons are (both) hadrons; (1) + (1)
protons and neutrons inside a nucleus are stable; (1)
free neutrons have half life of 10 - 15 minutes; (1)
free protons are stable / have half life of about 1032 year; (1)
5
allow equivalent marks for other hadrons and / or other relevant points
any
[5]
4.
(a)
hadron
baryon
lepton
neutron
proton
electron
neutrino
4 lines correct 2/2: 3 lines correct 1/2: 2 or 1 line correct 0/2 (2)
Mr Powell 2013
2
5
Mini Progress Check – Self, Peer or Teacher Assess
(b)
(c)
(i)
10–15 minutes - any value within range (1)
1
(ii)
weak force / interaction (1)
1
(iii)
d → u + e– + ν (-bar)
(u) (u)
(d) (d)
2
(iv)
charge: –1/3 (+ 2/3 –1/3) → 2/3 (+2/3 –1/3) –1 (+0) (1)
baryon number: 1/3 (+1/3 + 1/3) → 1/3 (+1/3 + 1/3) + 0 (+0) (1)
nuclear values:
charge 0 = 1 – 1 (+ 0) and baryon no. 1 = 1 + 0 gets 1/2
omits e– or ν loses 1 each (2)
(i)
arrowed line plus ‘resultant’ / pr label
(ii)
anti- (1) neutrino (1) is emitted
carried away some momentum (1)
shows neutrino momentum vector (1)
2
1
any 3
3
[12]
Mr Powell 2013
6