PEConservativeForces4A

PEConservativeForces4A - POTENTIAL ENERGY Often the work...

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1 POTENTIAL ENERGY Often the work done on a system of two or more objects does not change the kinetic energy of the system but instead it is stored as a new type of energy called POTENTIAL ENERGY. To demonstrate this new type of energy let‟s consider the following situation. Ex . Consider lifting a block of mass „m‟ through a vertical height „h‟ by a force F . Earth Earth M M h v i =0 v f =0 System = Block F mg m s 0 (since 0) 0 cos180 net if net F g o Fg WK K v v W W W W W mgh F W mgh System = block + earth Earth m F system s 0 net F Wnet K K W W mgh F W mgh Clearly the work done by F is not zero and there is no change in KE of the system. Where has the work gone into? Because recall that positive work means energy transfer into the system. Where did the energy go into? The work done by F ext must show up as an increase in the energy of the system. The work done by F ends up stored as POTENTIAL ENERGY (gravitational) in the Earth-Block System.
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This note was uploaded on 09/02/2011 for the course PHYS 4a taught by Professor Luna during the Spring '11 term at DeAnza College.

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PEConservativeForces4A - POTENTIAL ENERGY Often the work...

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