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Physics Definitions
Module 3 Work and Energy
Question | Answer |
---|---|
Work done by a force | The product of the force and the distance moved in the direction of the force |
The joule | This is a unit of energy 1J is the work done when a force of 1N moves it's point of application 1m in the direction for the force |
Conservation of energy | States that energy cannot be created or destroyed, just converted from one form to another or transferred from one place to another |
Power | Rate of work done. Measured in Watts |
The watt | A unit of power. 1 Watt is 1J of energy transferred per second |
Efficiency | The ratio of useful output energy to total input energy |
Tensile force | Usually two equal and opposite force acting on a wire in order to stretch it |
Compressive force | Two or more forces that have the effect on reducing the volume of the object on which they are acting or reducing the length |
Extension(x) | the change in length of an object when subjected to tension |
Elastic Limit | The point at which elastic deformation becomes plastic deformation |
Limit of proportionality | The point at which at which an object no longer obeys Hooke's law |
Force constant(k) | Force per unit extension or compression |
Hooke's law | The extensions of an elastic body is proportional to the force that causes it to up the limit of proportionality |
Elastic potential energy | The energy stored in a stretched or compressed object (E.G. a spring) |
Stress | The force per cross-sectional area. |
Strain | The extension per unit length |
Young's modulus(y) | The ratio between stress and strain |
Ultimate tensile strength | the maximum tensile force that can be applied to an object before it breaks |
Breaking stress | The maximum stress that can be applied to an object before it breaks |
Elastic deformation | The object will return to it's original shape when the deforming force has been removed |
Plastic deformation | The object will not return to it's original shape when the deforming force is removed, it becomes permanently deformed |
Ductile material | Materials that have a large plastic region and can therefore be drawn into a wire (E.G. copper) |
Brittle material | A material that distorts very little even when subject to a large stress and does not exhibit any plastic deformation (E.G. concrete) |
A polymeric material | A material made of many smaller molecules bonded together, often making a tangle knot of chains (E.G. rubber) these materials often exhibit very large strains (E.G. 300%) |