Calculating Energy from Intensity: A Super Nova Scenario

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A supernova releases 2.0×10^45 J of energy, and the scenario involves calculating how much energy reaches a 7 cm radius face located 1500 light-years away. The intensity of the energy is calculated using the formula I=P/A, but it becomes evident that this formula is not directly applicable since the total energy, rather than power, is given. The discussion highlights confusion about how to relate intensity to the energy received on the face, emphasizing the need for a different equation to connect these concepts. Participants express the challenge of finding the correct relationship in their study materials. The conversation underscores the importance of understanding the distinction between energy and power in astrophysical calculations.
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Homework Statement


A super nova releases 2.0×1045 J of energy. It is 1500 ly from earth. If you were facing the star in question, and your face was a circle 7 cm in radius, how much energy would reach your face?


Homework Equations


I=P/A


The Attempt at a Solution


I used I=P/A to get the intensity of the sun at the point of the face, but was unsure of how to use that number to determine the energy on 'my' face.
 
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Assume that the energy is uniformly distributed over the face of a sphere of radius 1500 ly.
 
but which equation would connect the energy to the intensity? =/
 
I = P / A isn't relevant here. You are given the total energy released, not the power (rate of energy release).
 
oh, well I feel silly.
hopefully I can find the equation I should use in my book.
 

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