6.2 AS Level

Elastic and plastic behaviour

7 flashcards to master this topic

Definition Flip

Define 'elastic deformation'.

Answer Flip

Elastic deformation is a temporary change in shape of a material when a stress is applied, and the material returns to its original shape when the stress is removed.

Example: A spring stretching and returning to its original length.
Definition Flip

Define 'plastic deformation'.

Answer Flip

Plastic deformation is a permanent change in shape of a material when a stress is applied, and the material does not return to its original shape when the stress is removed.

Example: Bending a metal wire and it stays bent.
Definition Flip

Define 'elastic limit'.

Answer Flip

The elastic limit is the maximum stress that a solid material can withstand before undergoing permanent deformation. Beyond this limit, the material will be plastically deformed.

Example: The point beyond which a spring will not return to its original length.
Key Concept Flip

What does the area under a force-extension graph represent?

Answer Flip

The area under a force-extension graph represents the work done in deforming the material or, equivalently, the elastic potential energy stored in the material. This is valid within the limit of proportionality.

Calculation Flip

State the formula for elastic potential energy (EP) in terms of force and extension, when within the limit of proportionality.

Answer Flip

EP = (1/2) * F * x, where F is the applied force and x is the extension. This formula applies only within the material's limit of proportionality (Hooke's Law).

Calculation Flip

State the formula for elastic potential energy (EP) in terms of the spring constant and extension, when within the limit of proportionality.

Answer Flip

EP = (1/2) * k * x², where k is the spring constant and x is the extension. This formula applies only within the material's limit of proportionality (Hooke's Law).

Key Concept Flip

How can you determine the elastic potential energy stored in a spring from a force-extension graph?

Answer Flip

The elastic potential energy is equal to the area under the force-extension graph, up to the point of extension considered. This area can be calculated using geometry (

Example: area of a triangle).

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