Define Young modulus .

The Young modulus is the ratio of tensile stress to tensile strain . It measures the stiffness of a material.

What are the units of the Young modulus , and why?

Pascals (Pa) , because strain is dimensionless.

The Young modulus is equal to the .......... of a stress-strain graph in the region where Hooke's law is obeyed.

The Young modulus is equal to the gradient of a stress-strain graph in the region where Hooke's law is obeyed.

What does the area under a stress-strain graph represent, in the linear region?

The energy stored per unit volume of the material.

True or False? The gradient of a stress-strain graph gives the Young modulus , even beyond the point where Hooke's law stops being obeyed.

False. The gradient only equals the Young modulus in the linear region , where Hooke's law is obeyed.

What is the aim of the required practical for the Young modulus ?

To measure the Young modulus of a metal in the form of a wire .

State the independent and dependent variables in the Young modulus required practical.

Independent variable: force (load) (N) Dependent variable: extension (m)

Name three variables that must be controlled in the Young modulus required practical.

Original length of the wire Thickness of the wire The metal used for the wire

What is the resolution of a micrometer screw gauge and of a metre ruler used in this experiment?

Micrometer: 0.001 mm Metre ruler: 1 mm

The Young modulus is calculated by multiplying the gradient of the load-extension graph by the ratio of the original length to the .......... of the wire.

The Young modulus is calculated by multiplying the gradient of the load-extension graph by the ratio of the original length to the cross-sectional area of the wire.

True or False? It is safe to continue taking readings on a wire that has been stretched past its elastic limit without checking it has returned to its original length.

False. Past the elastic limit , the wire is permanently deformed . The load should be removed and the wire checked to confirm it returns to its original length before taking new readings.

How can random error in the measured cross-sectional area of the wire be reduced?

By measuring the diameter of the wire in several places and calculating an average .

What two safety precautions should be taken when carrying out the Young modulus required practical?

Wear safety goggles at all times, in case the wire snaps Keep a cushion or soft surface directly below the mass hanger, in case it falls off

A LevelPhysicsAQAFlashcardsMechanics & MaterialsThe Young Modulus

The Young Modulus (AQA A Level Physics): Flashcards

Exam code: 7408

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Define Young modulus.

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Cards in this collection (15)

Define Young modulus.
The Young modulus is the ratio of tensile stress to tensile strain. It measures the stiffness of a material.
What are the units of the Young modulus, and why?
Pascals (Pa), because strain is dimensionless.
The Young modulus is equal to the .......... of a stress-strain graph in the region where Hooke's law is obeyed.
The Young modulus is equal to the gradient of a stress-strain graph in the region where Hooke's law is obeyed.
What does the area under a stress-strain graph represent, in the linear region?
The energy stored per unit volume of the material.
True or False?
The gradient of a stress-strain graph gives the Young modulus, even beyond the point where Hooke's law stops being obeyed.
False.
The gradient only equals the Young modulus in the linear region, where Hooke's law is obeyed.
State the equation for the Young modulus, E, in terms of force F, original length L, cross-sectional area A, and extension ΔL.
$E = \frac{F L}{A Δ L}$
What is the typical order of magnitude of the Young modulus for materials?
In the order of GPa (10⁹ Pa).
What is the aim of the required practical for the Young modulus?
To measure the Young modulus of a metal in the form of a wire.
State the independent and dependent variables in the Young modulus required practical.
- Independent variable: force (load) (N)
- Dependent variable: extension (m)
Name three variables that must be controlled in the Young modulus required practical.
- Original length of the wire
- Thickness of the wire
- The metal used for the wire
What is the resolution of a micrometer screw gauge and of a metre ruler used in this experiment?
- Micrometer: 0.001 mm
- Metre ruler: 1 mm
The Young modulus is calculated by multiplying the gradient of the load-extension graph by the ratio of the original length to the .......... of the wire.
The Young modulus is calculated by multiplying the gradient of the load-extension graph by the ratio of the original length to the cross-sectional area of the wire.
True or False?
It is safe to continue taking readings on a wire that has been stretched past its elastic limit without checking it has returned to its original length.
False.
Past the elastic limit, the wire is permanently deformed. The load should be removed and the wire checked to confirm it returns to its original length before taking new readings.
How can random error in the measured cross-sectional area of the wire be reduced?
By measuring the diameter of the wire in several places and calculating an average.
What two safety precautions should be taken when carrying out the Young modulus required practical?
- Wear safety goggles at all times, in case the wire snaps
- Keep a cushion or soft surface directly below the mass hanger, in case it falls off

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