PHYS144 Chapter 4: phys144_partD_WorkEnergy.pdf
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4 Feb 2015
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Work is done whenever a force is moved through a displacement that is not orthogonal to the direction of the force. Pushing a car does work against friction etc. Where the force is parallel to the distance moved. If the force is not parallel to the distance moved then the component of the force which is parallel must be used. If there is no component of the force parallel to the displacement then no work is done. Since work is force x distance it has s. i. units of newton- metres abbreviated to joule (j) This unit is named after the english physicist james joule who showed that heat energy could do mechanical work. Caloric theory stated that heat could be neither created or destroyed! Joule also discovered the heat dissipated by a resistor. Motivated by theology he also tried to demonstrate the unity of the forces of nature.