PotentialEnergyandConservati

- 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

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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 System = block + earth Earth m F system 0 (since 0) 0 cos180 net if net F g o Fg WK Kv v WW W WWm g h =∆ ∆= = = =+= =− F Wm g h = 0 net F Wnet K K m g h = ∆ == F g h = 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? Where did the energy go into? Because recall that positive work means energy transfer into the system. The work done by F must show up as an increase in the energy of the system.
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2 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 04/18/2011 for the course PHYS 151 taught by Professor Nassir,m during the Fall '08 term at University of Hawaii, Manoa.

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- 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

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