Work done on spring 2 2 if we stretch the spring

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Unformatted text preview: ey out of the bank decreasing Ugrav and spending it doing positive work 6 Physics 1001 Notes Conservation of mechanical energy (Gravitational forces only) • The sum K+Ugrav of kinetic and potential energy is called E, the total mechanical energy of the system o By system we mean the body of mass m and the earth considered together, because gravitational potential energy U is a shared property of both bodies o K1+Ugrav,1=K2 + Ugrav,2 (If only gravity does work) 12 12 o mv1 + mgy1 = mv2 + mgy2 (if only gravity works) 2 2 o E1= K1+Ugrav,1 and E2= K2 + Ugrav,2 o E is constant, thus it has the same value at y1 and y2 o A quantity that always has the same value is called a conserved quantity §༊ When only the force of gravity does work, the total mechanical energy is constant, that is it is conserved When other forces other then gravity work 12 12 • mv1 + mgy1 + wother = mv2 + mgy2 (If forces other then gravity 2 2 do work) • The work done by all forces other than the gravitational force equals the change in the total mechanical energy E=K +Ugrav of the system, where Ugrav is the gravitational...
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This note was uploaded on 04/09/2014 for the course PHYS 1001 taught by Professor Helenjohnston during the Three '13 term at University of Sydney.

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