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CAIE A-Level Physics 6 Deformation of Solids

Practise analysing deformation in solids, calculating stress, strain, Young modulus and elastic energy, and interpreting force-extension graphs and experimental evidence.

Syllabus
2028–2030
Course
Physics 9702
Level
AS

Exam points

  • analyse tensile and compressive deformation using force–extension ideas, Hooke’s law and spring constants
  • calculate stress, strain and Young modulus and assess a wire experiment from measured dimensions, loads and extensions
  • identify elastic, plastic and limiting behaviour from force–extension evidence
  • calculate work done and elastic potential energy from force–extension graph areas and the supplied elastic-energy formulae

Covered syllabus points

6.1 Stress and strain6.2 Elastic and plastic behaviour

6. Deformation of solids question 1

[Maximum number: 1]

The diagram shows a beam supported on two pivots.

Figure for Question 6. Deformation of solids question 1 — CAIE A-Level Physics AS

Which statement describes the state of the top surface X and of the bottom surface Y ?

A

Both X and Y are in compression.

B

Both X and Y are in tension.

C

X is in compression and Y is in tension.

D

X is in tension and Y is in compression.

6. Deformation of solids question 2

[Maximum number: 6]

One end of a wire is attached to a fixed point. A force F is applied to the wire to cause extension x. The variation with F of x is shown in Fig. 5.1.

Fig. 5.1

Fig. 5.1

The wire has a cross-sectional area of 4.1×10−7 m24.1 \times 10^{-7} \mathrm{~m}^{2} and is made of metal of Young modulus 1.7×1011 Pa1.7 \times 10^{11} \mathrm{~Pa}. Assume that the cross-sectional area of the wire remains constant as the wire extends.

Question (a)

(a)

State the name of the law that describes the relationship between F and x shown in Fig. 5.1.

[ 1 ]

Question (b)

(b)

The wire has an extension of 0.48 mm .

Determine:

[ 4 ]

Question (i)

(i)

the stress
stress = Pa

[ 2 ]

Question (ii)

(ii)

the strain.

strain =
[ 2 ]

Question (c)

(c)

A force of greater than 45 N is now applied to the wire.

Describe how it may be checked that the elastic limit of the wire has not been exceeded.

[ 1 ]

6. Deformation of solids question 3

[Maximum number: 9]

Fig. 4.1 shows the variation with extension x of the tensile force F for two wires, G and H, made from the same material.

Fig. 4.1

Fig. 4.1

The elastic limit has not been exceeded for G or H.

Question (a)

(a)

For the lines in Fig. 4.1:

[ 3 ]

Question (i)

(i)

state what is represented by the gradient

[ 1 ]

Question (ii)

(ii)

explain why the area under the line represents the elastic potential energy of the wire.

[ 2 ]

Question (b)

(b)

Wires G and H are joined together end-to-end to form a composite wire of negligible weight. The composite wire hangs vertically from a fixed support.

A block of weight of 2.0 N is attached to the end of the wire, as shown in Fig. 4.2.

Fig. 4.2

Fig. 4.2

[ 6 ]

Question (i)

(i)

Use Fig. 4.1 to determine:
- the extension xGx_{\mathrm{G}} of wire G

xG=x_{\mathrm{G}}=

mm
- the extension xHx_{\mathrm{H}} of wire H .

xH=x_{\mathrm{H}}=

mm

[ 1 ]

Question (ii)

(ii)

Calculate the total elastic potential energy EPE_{\mathrm{P}} of the composite wire due to the weight of the block.

EP=E_{P}=
[ 3 ]

Question (iii)

(iii)

The original length of wire G is L and the original length of wire H is 1.5 L.

Calculate the ratio

 cross-sectional area of wire G cross-sectional area of wire H\frac{\text { cross-sectional area of wire } \mathrm{G}}{\text { cross-sectional area of wire } \mathrm{H}}
ratio =
[ 2 ]
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