How Much Light Intensity Is Needed to Suspend a Sheet of Paper?

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To suspend an 8.5 by 11 inch sheet of black paper weighing 1.0 g in a vertical beam of light, a light intensity of 4.87x10^7 W/m^2 is calculated. The force acting on the paper is determined to be 9.8x10^-3 N, and the corrected area of the paper is 6.03x10^-2 m^2. There is a concern about the potential for the paper to burn due to the high intensity of light required. The calculations and assumptions made in the solution are being double-checked for accuracy. The discussion emphasizes the need for precise measurements and considerations in the experiment.
lunus
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Homework Statement


For a science project, you would like to horizontally suspend an 8.5 by 11 inch sheet of black paper in a vertical beam of light whose dimensions exactly match the paper.

If the mass of the sheet is 1.0 g, what light intensity will you need?

Homework Equations



Equation I used: F = IA/c


The Attempt at a Solution



F = 9.8x10^-3 N
A = 6.03 m^2
c = 3.00x10^8 m/s^2

I = Fc/A

I = 4.87x10^7 W/m^2

This is my attempt at the solution. I think its correct but I would like to double check. I would appreciate any help. thank you
 
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lunus said:

Homework Statement


For a science project, you would like to horizontally suspend an 8.5 by 11 inch sheet of black paper in a vertical beam of light whose dimensions exactly match the paper.

If the mass of the sheet is 1.0 g, what light intensity will you need?

Homework Equations



Equation I used: F = IA/c


The Attempt at a Solution



F = 9.8x10^-3 N
A = 6.03 m^2
c = 3.00x10^8 m/s^2

I = Fc/A

I = 4.87x10^7 W/m^2

This is my attempt at the solution. I think its correct but I would like to double check. I would appreciate any help. thank you

What's the area of that sheet of paper?
 
A = 6.03x10^-2 m^2

The area i had above was a typo
 
lunus said:
A = 6.03x10^-2 m^2

The area i had above was a typo

OK, no problem then.

Except that maybe it will burn up?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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