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Centre of Mass
Mark Scheme
Level
Subject
Exam Board
Unit
Topic
Difficulty Level
Booklet
Time Allowed:
GCSE
Physics
AQA
P3
Centre of Mass
Bronze Level
Mark Scheme
43 minutes
Score:
/43
Percentage:
/100
Page 1
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M1.(a)
concentrated
1
(b)
judge by eye
1
(c)
CAD
3 correct = 2 marks
1 or 2 correct = 1 mark
2
(d)
Lower the athlete’s seating position
1
Move the wheels further apart
1
[6]
M2.(a)
centre of X drawn at centre of pendulum bob
judged by eye
accept dot drawn at centre of circle
1
(b)
(i)
2
allow 1 mark for correct substitution, ie
subsequent step shown
provided no
2
(ii)
30or60 ÷ their (b)(i) correctly calculated
allow 1 mark for
or
or 0.5 × 60
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provided no subsequent step shown
2
(c)
51.2
allow 1 mark for correct substitution, ie 64 × 0.8 provided no
subsequent step shown
2
(d)
it increases (the moment)
must be comparative
accept 1 mark for calculation of the moment = 64 (Nm)
1
[8]
M3.
(a)
(i)
centre of X above the feet and in the body
a vertical line from their X falls between two lines in diagram
- judged by eye
1
(ii)
where the mass seems to be concentrated
accept it’s above the base (area)
accept because otherwise it would topple
accept line of action (of weight) passes through the base
do not accept where the mass is concentrated
1
(b)
any two from:
Page 3
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•
make (the area of) feet / base bigger
•
make feet wider apart
•
makes legs shorter / heavier
•
make head smaller / lighter
•
make tail touch the ground / make the tail longer
accept ‘make centre of mass / gravity lower’
2
[4]
M4.
(a)
below
1
(b)
boss
1
nail
do not allow boss
1
string
1
(c)
(i)
line from mid-point of either side to the mid-point of the opposite side
intention correct as judged by eye, use of ruler not essential
do not allow either diagonal
1
(ii)
X in the centre of the rectangle
1
[6]
Page 4
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M5.
(a)
centre of X
on the plumb lineand
between the level of the captions ‘plastic sheet’ and ‘hole B’
example
1
(b)
centre of mass
accept any unambiguous indication
1
(c)
vertical
accept any unambiguous indication
1
[3]
Page 5
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M6.
(a)
(i)
moment
1
(ii)
rotation
1
(iii)
the girl moves nearer to point P
1
(b)
(i)
X drawn in the centre of the space enclosed by the tyre
judge by eye
1
(ii)
below
1
[5]
M7.
(a)
X drawn at the centre of the tyre
judge by eye
1
(b)
(i)
second
1
(ii)
decreases it
1
[3]
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M8.
(a)
centre of X at the point where the axes cross
to within 1 mm in any direction
1
(b)
(i)
(at / in the) centre (of the tyre)
or unambiguously shown on the diagram
1
(ii)
(this is) where axes of symmetry (of the tyre) cross / intersect / meet
or point at which the mass of the tyre seems to be
(concentrated)
1
[3]
M9.
(a)
centre of X should appear to be on the continued line of the flex and in the
body of the lamp as judged by eye
example
1
(b)
below
1
(c)
(D)→B→F→A→C→(E)
all four correct for 3 marks
or any two correct for 2 marks
or just one correct for 1 mark
3
[5]
Page 7
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Page 8