Deformation of solids

• Deformation is caused by force
• Tensile forces - causes an object to be stretched
• Compressive forces - causes an object to be squashed or compressed
• Extension - increase an object's length
• Hooke's law - the extension produced is proportional to the applied force as long as the limit of proportionality hasn't been reached
• Limit of proportionality - point beyond which the extension is no longer proportional to the force
• Spring constant - force per unit extension
• Elastic deformation - when deforming forces are removed, spring returns back to the original length
• Plastic deformation - when deforming forces are removed, spring does not return back to original length
• Elastic limit - maximum stress that can be applied before causing plastic deformation
• Stress - force applied per unit cross sectional area
• Strain - fractional increase in original length of wire
• Young's modulus - ratio of stress over strain
• Young's modulus describes the stiffness of a material
• Elastic potential energy or strain energy - the potential energy stored in or work done by an object when it is deformed elastically
• Strain energy = area under the fx graph