Physics 101- Introduction to Mechanics
March 13- Conservation of Energy






  Work Done by a Spring
A 250 g stone is dropped onto a vertical spring with spring constant 2.5 N/cm.  The stone becomes attached to the spring and the spring compresses 12 cm before momentarily stopping.  What is the speed of the block just before it hits the spring?

Now let's do the problem with the system as the stone, spring and earth.  What is the change in energy within the system?  (How much energy enters or leaves the system?)

Now we must define some new types of energy.  If we are not allowing energy to flow in or out of the system then, the energy is in some other form within the system after is has been converted from kinetic energy.  These "stored" energies are the potential energies.


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Jeff Phillips
Loyola Marymount University
Spring 2002