This document outlines key concepts of elasticity: 1) An elastic body regains its original shape and size after being stretched or compressed. 2) According to Hooke's law, the extension (e) of an elastic material is directly proportional to the applied force (F). 3) Young's modulus relates tensile stress to tensile strain, and the work done on springs and elastic strings can be calculated as one-half the force times the extension or one-half the elastic constant times the extension squared.

1. PHYSICS
ELASTICITY basics
Short revision series

2. This powerpoint highlights the
basics you should know before
you commence attempting the
questions.

3.  An elastic body regains its original shape
and size after being stretched or compressed
 Hooke’s law: The extension (e) in an elastic
material is proportional to the load or
applied force F.
 F α e
 F = ke ......................k = elastic constant

4. Young’s modulus
 Tensile stress => force/area = F/A
Tensile strain extension/lenght e/l

5. Energy and work done on springs
and elastic strings
 Work is done when an elastic material is
stretched or compressed
 W = average force x extension = ½ Fe
 Remember from Hooke’s law F = ke
 W = ½ ke x e = ½ ke2

6. Elastic potential energy
 Elastic potential energy is also given as =>
½ Fe = ½ ke2
This is because the elastic potential is stored
energy tht can be used to stretch or compress
an elastic material.
During compression or extension the stored
energy is used to do the work. So the same
potential energy is onverted to kinetic energy
during the process.
Remember Law of conservation of energy,
PE+KE = 0; PE = KE