EXSS1018 Lecture 10: Week 10 Notes
4 Sep 2018
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Document Summary
Total momentum of a system remains constant. An object must be moved a distance for work to occur. Work is equal to the change in energy that it produces in the object. Gravity does not change total energy of an object. When slowing down - work is negative. Change in kinetic energy of an object = net work done on object. Negative takes energy away from an object (absorbing energy) Energy decreases on contact with a surface. The surface energy will increase at contact. Concentric = develops force and shortens (positive work) Eccentric = develops force and lengthens (negative work absorbs energy) Body gets slower = loses kinetic/potential energy. Isometric = develops force by no change in length. No work done = no mechanical energy. Measure of amount of work done for a given amount of energy intaken. Human body efficiency = 20% (1000j of energy used = 200j work done) Rate of doing work rate of expending energy.
