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Re: [Phys-L] Energy & Bonds



-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Paul Lulai
Sent: Wednesday, November 13, 2013 9:37 AM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] Energy & Bonds

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I am still having issues with one (at least) concept. Endo-thermic graphs (like
this one: http://bit.ly/184Ow3E
Here's an analogy that might prove useful to you. A person picks a dog-food bowl up off of the kitchen floor and puts it into the kitchen sink. At first the person increases the gravitational potential energy of the bowl-earth system by adding enough energy to it to get it up over the rim of the sink. This is analogous to the activation energy in the endothermic chemical reaction. Then the bowl does positive work on the person as the person lowers the bowl down into the bottom of the sink, that is the gravitational potential energy of the bowl-earth system decreases. The net result is that the bowl-earth system has a greater amount of gravitational potential energy than it started with (greater by mgh where m is the mass of the bowl and h is how high the bottom of the sink is above the floor).