Calculating Energy from Intensity: A Super Nova Scenario

[Aeighme]

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.

 

[edziura]

Assume that the energy is uniformly distributed over the face of a sphere of radius 1500 ly.

 

[Aeighme]

but which equation would connect the energy to the intensity? =/

 

[edziura]

I = P / A isn't relevant here. You are given the total energy released, not the power (rate of energy release).

 

[Aeighme]

oh, well I feel silly.
hopefully I can find the equation I should use in my book.