Oxford Revise AQA GCSE Combined Science Foundation | Chapter P8 answers

P8: Forces

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

force = spring constant × extension

1

AO1

6.5.3

01.2

2 = spring constant × 0.01

\(\rm{spring\ constant} =
\frac{2}{0.01}
\)

= 200 (N/m)

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1

1

AO2

6.5.3

01.3

work done = 0.5 × 200 × (0.01)2

= 0.01 J

1

1

AO2

6.5.3

01.4

correct suggestion e.g.,

use a newtonmeter/weights to measure the extension for different forces

repeat several times and find the average extension

plot a graph of force against extension

if the graph is a straight line then the relationship is linear

1

1

1

1

AO1

6.5.3

02.1

a vector has magnitude and direction

1

AO1

6.5.1.1

02.2

weight

magnetism

1

1

AO1

6.5.1.2

02.3

e.g., water resistance/drag, upthrust/buoyancy, tension

1

AO1

6.5.1.2

03.1

An arrow pointing to the left.

1

AO1

03.2

no

the desk is pushing up (so there are two forces)

1

1

AO3

6.5.3

03.3

three

1

AO3

6.5.3

03.4

elastic deformation

1

AO1

04.1

newtons

1

AO2

6.5.1.3

04.2

\(
\frac{20\ + \ 21\ + \ 23}{3} = 21.3
\)

21

answer given to two significant figures

1

1

AO2

6.5.1.3

04.3

one mark for correctly plotted point

one mark for line of best fit

2

AO2

AO3

6.5.1.3

04.4

the weight is proportional to the mass/there is a linear relationship

1

AO3

6.5.1.3

05.1

non-contact – weight/force of the Earth on the wood

1

AO1

AO2

4.5.1.2

05.2

contact force – upthrust/upwards force of the water on the wood

1

AO1

AO2

4.5.1.2

05.3

equal

opposite

do not accept ‘they are balanced’ or ‘they cancel out’

1

1

05.4

water resistance

contact force

1

1

AO1

AO2

4.5.1.2

06.1

mass — a measure of the amount of material in an object

weight — is a measure of the force of gravity on an object

one mark for one line correct

two marks for both lines correct

2

AO1

6.5.1.3

06.2

a region where the force of gravity acts

1

AO1

6.5.1.3

06.3

mass

N/kg

mass

weight

1

1

1

1

AO1

6.5.1.3

07.1

the resultant force is the single force that has the same effect as all the forces acting together

1

AO1

6.5.1.4

07.2

zero

1

AO2

6.5.1.4

07.3

2000 N

to the left

1

1

AO2

6.5.1.4

08.1

the force of the hand on the bag

1

AO2

4.5.3

08.2

inelastic deformation is deformation where the object does not return to its original shape when the force is removed

1

AO1

4.5.3

08.3

Statement

Correct

the graph for the plastic bag shows a non-linear relationship between force and extension

the graph for the plastic bag shows that is proportional to extension

a graph that is a straight line is likely to be for a spring

the material that produced a linear graph has been inelastically deformed

one mark for each correct row

2

AO3

4.5.3

09.1

2 cm = 0.02 m

elastic potential energy = 0.5 × 2000 × 0.022

= 0.4

J (joules)

1

1

1

1

AO1

AO2

6.5.3

09.2

bigger

the elastic potential energy stored/work done is proportional to the spring constant: elastic potential energy stored = 0.5 × spring constant × extension2; if the compression is the same but the work done is bigger, then the spring constant must be bigger

1

1

AO3

6.5.3

09.3

yes

the elastic potential energy stored in a spring is the same when it is extended by 1 cm as when compressed by 1 cm. The elastic potential energy stored is equal to the work done, so the same amount of work will be done (if the average force applied is the same).

1

1

AO2

6.5.3

10.1

work done = force × distance

accept W = Fs

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AO1

4.5.2

10.2

work done = 20 × 30

= 600 (Nm or J)

accept 600 (Nm or J) with no working for the two calculation marks

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1

AO2

4.5.2

10.3

friction

1

AO1

4.5.2

10.4

energy is transferred from the chemical energy store (food/oxygen)

to the thermal energy store (of the surroundings)

do not accept answers involving kinetic energy

1

1

AO2

4.5.2

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