Understanding Physics: Gravitational Potential Energy

AI Thread Summary
The discussion centers on understanding gravitational potential energy (Ug) and the related terms Us and Uint in a physics context. Participants express confusion about the definitions of Us and Uint, suggesting that Us might refer to the soccer ball and Uint to internal potential energy changes. The initial kinetic energy of the ball, influenced by the goalkeeper's kick, raises questions about quantifying the work done. It is noted that consulting a physics handbook or seeking help from instructors may be necessary for clarity. The impact of air friction on energy conservation in the system is also acknowledged as a complicating factor.
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Homework Statement



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The Attempt at a Solution



I know Ug stands for the gravitational potential energy, but I'm not sure what Us and Uint stands for.

At initial stage 1, I know the ball has kinetic energy and also has had work applied on it (the goalkeeper kicking the ball), but how do I know how much work is being applied?
 
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You are in serious trouble with this question. I think you would need to consult your Physics handbook to solve it (or get help from the lecturer/other scolars in the class).

My guess is that the g refers to the Earth and the s refers to the soccer ball while the int refers to a change in internal potential energy. It is not clear (at all) what is on the x- and y-axii. That is why I think you should look in the handbook or ...

My take on it is that the goalkeeper injects energy into the ball/earth system by kicking it. If air friction were not present the sum of all energies would remain constant, but I have a sneaky fealing that in this case one should assume that air friction removes energy from the system.
 
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LOL. Oh well, I tried!
 

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