WJEC 2014 Online Exam Review
GCSE Physics Unit 2 4473-01
All Candidates' performance across questions
Question Title
1
2
3
4
5
6
7
N
4880
4881
4809
4876
4853
4875
4736
Mean
7
5.4
2.8
3.5
3.5
6.9
2.5
SD
1.3
1.4
1.7
1.2
1.8
2.2
2.1
Max Mark
9
7
6
5
9
12
12
FF
77.4
77
46.5
70.2
38.9
57.8
21.2
Attempt %
100
100
98.5
99.9
99.4
99.9
97
GCSE Physics Unit2 4473-01
7
21.2
Question
6
57.8
5
38.9
4
70.2
3
46.5
2
77
1
77.4
0
10
20
30
40
50
60
Facility Factor %
70
80
90
100
3
6
7
7
3. The mass of a sample of a radioactive isotope is 64 g and it has a count rate of 800 counts per
minute. It is a gamma emitter.
It has a half-life of 30 minutes.
Radioactive decay follows the pattern below:
Original
amount of
radioactive
isotope
(a)
One
half-life
Amount
remaining
is halved
Another
half-life
Amount
remaining
is halved
again
Another
half-life
Examiner
only
Amount
remaining
is halved
again
(i) Find out how many half-lives it takes for the count rate to fall to 50 counts per
minute.[1]
.................................
(ii) How long does it take for the count rate to fall to 50 counts per minute?
[2]
4 473
010 0 07
time = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(iii) What mass of the radioactive isotope remains at this time?
[1]
mass = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . g
(b)
Explain why this radioactive isotope would be suitable as a radioactive tracer in medicine.
[2]
6
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12
6. A car is moving at a speed of 15 m/s. A child runs out into the road causing the driver to make
an emergency stop.
(a)
The graph shows how the speed of the car changes from the moment the driver sees the
child.
Speed (m/s)
15
10
5
0
0
1
2
3
4
Time (s)
(i) What was the reaction time of the driver?
[1]
..................................
(ii) How long did it take the car to stop once the brakes were applied? [1]
..................................
(iii) Use an equation from page 2 to calculate the deceleration of the car. s
s
[2]
deceleration = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m/s2
(iv) Explain how the graph would be different for a driver who had drunk alcohol.
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[2]
Examiner
only
13
(v) Explain how the graph would be different if it had been a wet day. [2]
Examiner
only
(b) In an emergency stop, the driver in the car moves forward before being stopped by the
seat belt.
The graph shows the force exerted by the seat belt on the driver during the emergency
stop.
Force exerted by seat belt (N)
300
200
100
0
0
10
20
30
Distance moved by the driver (m)
(i) Use an equation from page 2 to calculate the work done to stop the driver. work done = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J
[3]
(ii) How much energy is transferred from the driver during the emergency stop?
[1]
.........................................
J
12
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7. Nuclear fission and nuclear fusion are examples of nuclear reactions. Typical nuclear fission
and nuclear fusion reactions are shown below.
(i) Complete the equation for the first reaction.
(a)
235
92 U
+
1
0n
2
1H
90
......
+
Sr +
3
1H
4
2 He
[2]
144
54 Xe
+
+
......
1
0n
1
0n
(ii) Explain how the first reaction could lead to an uncontrolled chain reaction.
[2]
(b)
2
1H
3
and 1 H are both isotopes of hydrogen.
Compare the structure of the nuclei of these two isotopes. © WJEC CBAC Ltd.
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[2]
Examiner
only
15
(c) Nuclear fission and nuclear fusion both produce heat energy. Describe and compare
nuclear fission and nuclear fusion reactions.
[6 QWC]
Examiner
only
Include in your answer:
• what happens in each of the reactions;
• the problems associated with each reaction.
(You are not required to include any detail on moderators or control rods.)
12
END OF PAPER
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