# Elasticity

Card 1: What is elasticity

## Elasticity

Elasticity is the ability of a sub-stance to recover its original shape and size after distortion.

Card 2: Forces between atoms

## Forces Between Atoms The intermolecular forces consist of an attractive force and a repulsive force.

• At the equilibrium distance d, the attractive force equal to the repulsive force.
• If the 2 atoms are brought closer, the repulsive force will dominate, produces a net repulsive force between the atoms.
• If the 2 atoms are brought furhter, the attractive force will dominate, produces a net attractive force between the atoms.
Card 3: Graph of Resultant Force against the Distance between 2 Atom

## Graph of Forces Between 2 atoms x0 = Equilibrium Distance

When the particles are compressed, x < x0, the repulsive force between the particles increases.

When the particles are stressed, x > x0, the attractive force between the particles increases.

If the distance x exceeds the elastic limit, the attractive force will decreases.

Card 4: State Hooke's Law

## Hooke's Law

Hooke's Law states that if a spring is not stretched beyond its elastic limit, the force that acts on it is directly proportional to the extension of the spring.

Card 5: What is elastic limit?

## Elastic Limit

The elastic limit of a spring is defined as the maximum force that can be applied to a spring such that the spring will be able to be restored to its original length when the force is removed.

Card 6: Equation derived from Hooke's Law

## Equation derived from Hooke's Law

From Hook's Law, we can derived that Card 7: What is spring constant?

## Spring Constant

Spring constant is defined as the ratio of the force applied on a spring to the extension of the spring. It is a measure of the stiffness of a spring or elastic object.

Card 8: Graph of Streching Force against Spring Extension

## Graph of Streching Force - Extension Area below the graph = Work done

Card 9: F - x Graph and Spring Constant

## F-x graph and spring constant The higher the gradient, the greater the spring constant and the harder (stiffer) spring.

For example, the stiffness of spring A is greater than spring B.

Card 10: System of Spring

## System of Spring Arrangement in series:
Extension = x × number of spring
Stiffness decreases
Spring constant = k/number of spring

Arrangement in parallel:
Extension = x ÷ number of spring
Stiffness increases
Spring constant = k × number of spring

Factors Affecting the Stiffness of Spring

## Factors Affecting the Stiffness of Spring

 Stiffer Less stiff Material type of spring  Diameter of wire of spring  Diameter of the spring  Length of the string   Table of Content

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