Physics 9702 · Paper 1

Deformation of Solids

Definitions: Deformation of Solids

One exam question, the mark-scheme answer, and the exact phrases that score (highlighted, then listed below in the same colour).

Exam question

State Hooke's law.

1 mark

Model answer

Hooke's law: the extension is proportional to the force, below the limit of proportionality.

Marking points

1 mark each

1extension is proportional to the force, below the limit of proportionality(1)

Exam question

Define stress.

1 mark

Model answer

Stress is force per unit cross-sectional area.

Marking points

1 mark each

1force per unit cross-sectional area(1)

Exam question

Define strain.

1 mark

Model answer

Strain is extension per unit original length.

Marking points

1 mark each

1extension per unit original length(1)

Exam question

Define the Young modulus.

1 mark

Model answer

The Young modulus is stress / strain.

Marking points

1 mark each

1stress / strain(1)

Exam question

State what is meant by elastic deformation.

1 mark

Model answer

Elastic deformation: the object returns to its original shape when the load is removed.

Marking points

1 mark each

1returns to its original shape when the load is removed(1)

Exam question

State what is meant by plastic deformation.

1 mark

Model answer

Plastic deformation: the object does not return to its original shape when the load is removed.

Marking points

1 mark each

1does not return to its original shape when the load is removed(1)

Exam question

State what is meant by the limit of proportionality.

1 mark

Model answer

The limit of proportionality is the point beyond which extension is no longer proportional to force.

Marking points

1 mark each

1point beyond which extension is no longer proportional to force(1)

Exam question

State what is meant by the elastic limit.

1 mark

Model answer

The elastic limit is the point beyond which the deformation becomes permanent.

Marking points

1 mark each

1point beyond which the deformation becomes permanent(1)

Exam question

State what is meant by the elastic potential energy stored in a deformed object.

1 mark

Model answer

Elastic potential energy is the energy stored in an object because of its (elastic) deformation (within the linear region, $E_p = \tfrac{1}{2}Fx = \tfrac{1}{2}kx^2$ ).

Marking points

1 mark each

1energy stored in an object because of its (elastic) deformation(1)

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Deformation of Solids

Definitions: Deformation of Solids

One exam question, the mark-scheme answer, and the exact phrases that score (highlighted, then listed below in the same colour).

Exam question

State Hooke's law.

1 mark

Model answer

Hooke's law: the extension is proportional to the force, below the limit of proportionality.

Marking points

1 mark each

1extension is proportional to the force, below the limit of proportionality(1)

Exam question

Define stress.

1 mark

Model answer

Stress is force per unit cross-sectional area.

Marking points

1 mark each

1force per unit cross-sectional area(1)

Exam question

Define strain.

1 mark

Model answer

Strain is extension per unit original length.

Marking points

1 mark each

1extension per unit original length(1)

Exam question

Define the Young modulus.

1 mark

Model answer

The Young modulus is stress / strain.

Marking points

1 mark each

1stress / strain(1)

Exam question

State what is meant by elastic deformation.

1 mark

Model answer

Elastic deformation: the object returns to its original shape when the load is removed.

Marking points

1 mark each

1returns to its original shape when the load is removed(1)

Exam question

State what is meant by plastic deformation.

1 mark

Model answer

Plastic deformation: the object does not return to its original shape when the load is removed.

Marking points

1 mark each

1does not return to its original shape when the load is removed(1)

Exam question

State what is meant by the limit of proportionality.

1 mark

Model answer

The limit of proportionality is the point beyond which extension is no longer proportional to force.

Marking points

1 mark each

1point beyond which extension is no longer proportional to force(1)

Exam question

State what is meant by the elastic limit.

1 mark

Model answer

The elastic limit is the point beyond which the deformation becomes permanent.

Marking points

1 mark each

1point beyond which the deformation becomes permanent(1)

Exam question

State what is meant by the elastic potential energy stored in a deformed object.

1 mark

Model answer

Elastic potential energy is the energy stored in an object because of its (elastic) deformation (within the linear region, $E_p = \tfrac{1}{2}Fx = \tfrac{1}{2}kx^2$ ).

Marking points

1 mark each

1energy stored in an object because of its (elastic) deformation(1)